Stratigraphy and Petrology of the Permian Rocks of ...

Stratigraphy and Petrology

of the Permian Rocks of

Southwestern Montana

GEOLOGICAL SURVEY PROFESSIONAL PAPER 313-C

Prepared on behalf of the

U.S. Atomic Energy Commission

Stratigraphy and Petrology

of the Permian Rocks of

Southwestern MontanaBy EARLE R. CRESSMAN and ROGER W. SWANSON

GEOLOGY OF PERMIAN ROCKS IN THE WESTERN PHOSPHATE FIELD

GEOLOGICAL SURVEY PROFESSIONAL PAPER 313-C

Prepared on behalf of the

U.S. Atomic Energy Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1964

UNITED STATES DEPARTMENT OF THE INTERIOR

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing OfficeWashington, D.C. 20402

CONTENTS

Abstract _ ______________________________Introduction. ____________________________

Purpose of investigation. ______________Personnel and acknowledgments. _ ______Geography _______________________Geologic setting. _____________________Methods of study _ __________________

Field procedures__________________Laboratory procedures. ___________

Treatment of channel samples. _ Chemical analyses. ___________

P2 O5 _ ________... ________Acid insoluble. ___________Uranium ___ ____________Carbonaceous matter __ __ Spectrographic analyses ___ Other analyses___________

Petrographic methods_____________Examination of hand specimens Thin sections_________________Size analyses_________________Heavy-mineral separation _ ___

Terminology ___________________________________Explanation of illustrations______________________

Stratigraphy and petrography. _______________________Stratigraphic nomenclature ______________________

History of nomenclature.. _ __________________Current nomenclature. ______________________

Park City Formation __ ________________________General character and distribution. ___________Lithology _______________________________

Carbonate rock _ ______________________Sandstone _____________________________Mudstone ___ _________________________Chert. _____ _ _ __ _______ ___ _______

Stratigraphy. ____ _ _______________________Grandeur Member.. ____________________Franson Member.... ___________________

Phosphoria Formation __ _______________________General character and distribution. ___________Lithology _______________________________

Frequency of rock types. ________________Occurrence of carbonaceous matter in the

Retort Phosphatic Shale Member_______Phosphorite. ___________________________Mudstone ___ _ ________________________Carbonate rock_________________________Chert_ ----._____..____.___.__.___.____Minor rock types_______________________Trace elements_________________________Contact metamorphism_.________________

Page275276276276276277278278279279279279280280280280280280280280281281281282282284284284285286286289289292294296296296300303303305305

3053073 13315315317318319

Stratigraphy and petrography Continued Phosphoria Formation Continued

Stratigraphy. _________-__-___---_--_--_----Meade Peak Phosphatic Shale Member_ _

Lower phosphorite._________________Rex Chert Member. ____________________Retort Phosphatic Shale Member_________Tosi Chert Member__________-----____-_Cherty shale member__________-_________

Localization of exploitable phosphate deposits. _ Shedhorn Sandstone.____________________________

General character and distribution____________Lithology-_ __________--_----_-_------------

Sandstone.________---_-__-------------Chert._________-__------------_-------Dolomite _______-___--_----------------

Stratigraphy ____________--._____--------_-_-Lower member_________________----_---Upper member____________-_-_---_----_

Age of Permian rocks in southwestern Montana. Relation of Permian strata to overlying beds.______Facies relations.__________-___-__-___---_-_-----

Genetic interpretations__________-_-____-_-----------Origin of the rock types__ _________-_--_---------

Well-sorted sandstone_____________----_----_Lithologic character of source.___________Location of source_-_--___----_---------Environment of deposition_______________Significance of glauconite________________

Silty sandstone and tan and red mudstone-____Lithologic character of source ____________Location of source____-___-___--_-----_-Environment of deposition.. ______ _______

Chert. __________ - --- Source of silica.___________---------__--Environment of deposition_______________Diagenesis _____-__----_---_------------

Dark mudstone___________________________Source of detritus-_-__-__----___--------Source of carbonaceous matter. __________Rate of production of carbonaceous matter. Environment of deposition.-.____________

Phosphatic mudstone-______________---__----Solubility of apatite_-_-____---------_-_-Source of phosphorus.___________________Manner of deposition ___________________Origin of pellets. _____________-------_-_Bimodal frequency distribution of mud-

stone. _____________--___----_---__---Summary. _______________-___--_-----__

Phosphorite-_________-__-----__--_---------Carbonate rock_____________________±f_______

Park City Formation.___________________in

Page 320 320 323 325 329 336 336 338 338338339339347347347347350354354355357359359359361364367367367367367369369371371373373373373374374374374374375

376376377378378

IV CONTENTS

Genetic interpretations ContinuedOrigin of the rock types Continued

Carbonate rock Continued Page Phosphoria formation ___________________ 378

Paleogeography _ ________________________________ 378Tectonism _____________________________________ 380

Genetic interpretations Continued Page Summary of Permian events in southwestern

Montana ____________________________________ 381Stratigraphic sections.-_____________________________ 383

Introduction ___________________________________ 383References cited____________________________________ 562

Transgression and regression, ____________________ 380 Index__ ___________________________________________ 567

ILLUSTRATIONS

[Plates are in separate volume]

PLATE 14. Index map of southwestern Montana.15. Map showing outcrops of Permian rocks in southwestern Montana and localities sampled for Phosphate.

16-24. Stratigraphic sections showing relations of the:16. Grandeur member of the Park City Formation from Hawley Creek, Idaho, to Indian Creek, Mont.17. Grandeur Member of the Park City Formation from Crooked Creek to Big Hole Canyon, Mont.18. Phosphoria and Shedhorn Formations and the Franson Tongue of the Park City Formation from

Sheep Creek to Reas Peak, Mont.19. Phosphoria, Shedhorn, and Park City Formations from Kelly Gulch to the Sixteen Mile Creek area,

Mont.20. Phosphoria and Shedhorn Formations and the Franson Member of the Park City Formation from

Little Sheep Creek to the Melrose area, Mont.21. Phosphoria and Shedhorn Formations and the Franson Member of the Park City Formation from

Hawley Creek, Idaho, to Cinnabar Mountain, Mont.22. Phosphoria, Shedhorn, and Park City Formations from North Boulder Creek, Mont, to Quadrant

Mountain, Wyo.23. Retort Phosphatic Shale Member of the Phosphoria Formation from Big Sheep Canyon to West

Fo.k of Madison River, Mont.24. Stratigraphic relations of the Retort Phosphatic Shale Member of the Phosphoria Formation from

Crooked Creek to La Marche Gulch, Mont. 25. Maps showing Paleography in Southwestern Montana.

Page FIGURE 87. Bulldozer trench at Sheep Creek____________________________-_--_-_--___---------_-----------_- 278

88. Retort Phosphatic Shale Member of the Phosphoria Formation exposed in bulldozer trench at GreenstoneGulch_____________ ______________________________________________________________ 278

89-90. Graphs comparing:89. Original and rerun uranium analyses of 22 samples of phosphorite collected in 1949 ____________ 28190. Sieve and thin-section size analyses__-_________________________________.____-_--------_--- 282

91. Diagram showing relation of class areas and D values to composition in a three-component system_____ 28392. Isopach map of Permian rocks in southwestern Montana ___________________________________________ 28493. Chart showing nomenclature of the Phosphoria, Park City, and Shedhorn Formations..._______________ 286

94-95. Maps showing:94. Lithologic character of the Permian rocks in southwestern Montana.___________________________ 28795. Constitution of the Permian of southwestern Montana by formations.__________________________ 288

96. Isopach map of the Park City Formation.._____________________----_-_-____________------_------- 28997. Map showing lithologic character of the Park City Formation.._____________________________________ 29098. Graph indicating thickness of bedding of dolomite in the Grandeur Member of the Park City Formation__ _ 29199. Cumulative size distribution curves for six mudstones from the Grandeur Member of the Park City Forma

tion____________________________________________________________________________________ 295100. Isopach map of the Grandeur Member of the Park City Formation._________________________________ 298101. Map showing lithologic character of the Grandeur Member of the Park City Formation________________ 299102. Isopach map of the Franson Member of the Park City Formation.__________________________________ 301103. Map showing lithologic character of the Franson Member of the Park City Formation.________________ 302104. Isopach map of the Phosphoria Formation__---_-----___-----___---_--_-_-----_----------_-------- 304

105-106. Diagrams showing:105. Mineral composition of rock types in the Retort Phosphatic Shale Member of the Phosphoria

Formation _________________________________________________________________________ 306106. Relation of content of carbonaceous matter to rock composition in the Retort Phosphatic Shale

Member of the Phosphoria Formation.________________________________________________ 307

CONTENTS V

FIGTJBE 107-109. Graphs showing: Page107. Frequency distribution of carbonaceous matter in the Retort Phosphatic Shale Member of the

Phosphoria Formation.______________________________________________________________ 308108. Frequency distribution of value (darkness) for phosphorite of the Retort Phosphatic Shale Member

of the Phosphoria Formation_________________________________________________________ 308109. Effect of weathering on value (darkness) of phosphorite___________-__--__--___-___-_-_-_--- 309

110. Photomicrograph of cherty phosphorite containing abundant foraminiferal tests as nuclei of pellets.______ 309111. Diagram showing relative abundance of the three principal types of apatite grains in thin sections of phos

phorite from the Phosphoria Formation. _____________________________________________________ 310112. Photomicrographs of phosphorites_______________________________________________________________ 311

113-114. Graphs illustrating:113. Size distribution of pellets in a muddy pelletal phosphorite___________________________________ 312114. Value (darkness) of mudstone of the Retort Phosphatic Shale Member of the Phosphoria Forma

tion, ________________________________________________________ 314115. Photomicrographs of chert from the Tosi Chert Member of the Phosphoria Formation.________________ 318116. Very sandy phosphorite from top of phosphatic sandstone bed underlying 4-foot andesite(?) porphyry sill

at Jack Canyon, Madison Range. ___________________________________________________________ 321117. Isopach map of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation_______________ 322

118-119. Maps showing:118. Lithologic character of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation. _ 324119. Thickness of beds of carbonate rock in the Meade Peak Phosphatic Shale Member of the Phosphoria

Formation. _________________________________________-_--__--_---____-_------ 325120. Isopach map of the basal phosphorite bed of the Meade Peak Phosphatic Shale Member of the Phosphoria

Formation. _____._________.__________________________________________ 326121. Map showing character of apatite grains in the lower phosphorite of the Meade Peak Phosphatic Shale

Member of the Phosphoria Formation..______________________________________________________ 327122. Isopach map of the Rex Chert Member of the Phosphoria Formation________________________________ 328

123-126. Maps showing:123. Thickness and P2O5 content of the Retort Phosphatic Shale Member of the Phosphoria Forma

tion, ________________________________________________________ 330124. Lithologic character of the Retort Phosphatic Shale Member of the Phosphoria Formation_______ 331125. Percent carbonate rock in the Retort Phosphatic Shale Member of the Phosphoria Formation.___ 332126. Content of carbonaceous matter in the Retort Phosphatic Shale Member of the Phosphoria Forma

tion _______________________________________________________________________________ 333127. Diagram showing mineral composition of rocks in three facies of the Retort Phosphatic Shale Member of

the Phosphoria Formation___________________________________-_-_-___--------____-__-------- 334128. Isopach map of the Tosi Chert Member of the Phosphoria Formation._______________________________ 337129. Type locality of Shedhorn Sandstone__..____________________________________________ 339130. Isopach map of the Shedhorn Sandstone_________________________________--__------_-_-___------ 340

131-132. Graphs showing:131. Summary of size distribution data of Permian sandstone.______-_____-__-_____-_-_--__-----_- 341132. Relation between coefficient of sorting (So) and phi median diameter (Md<£)____________________ 342

133. Photomicrograph of sandstone from the base of the upper member of the Shedhorn Sansdtone at SheepCreek____________________________________________________________________________________ 343

134. Graph comparing size distributions of zircon and tourmaline with that of total sample__________________ 343135. Graph showing composition by weight of heavy accessory minerals in bed Us-124, lot 1234______________ 344136. Diagram showing relative abundance of tourmaline color varieties.___________________________________ 345

137-138. Graphs showing:137. Tourmaline of Shedhorn Sandstone classified by roundness and type of inclusions.______________ 346138. Color of Shedhorn Sandstone-.--.---------.------___.._____________-__---_-_ ------ 348

139-140. Isopach maps of the:139. Lower member of the Shedhorn Sandstone._________________-----_-_----------------------- 349140. Upper member of the Shedhorn Sandstone._______---_-_--__------------------------------- 350

141. Columnar concretions of sandstone, cherty sandstone, and sandy chert from Permian rocks in Madison andGallatin Ranges, Montana.._______________________________---_----------------------------- 352

142-148. Maps showing distribution of facies in:142. Late Grandeur time.______________________________-____-_---_--------------------------- 356143. Rex time. _ ______ ____ _____-_-____--_-_-- -- -- - -- 358144. Franson time._________________________________________--__--------_----_--------------- 359145. Middle Franson time_______-____-__________---_-_--------------------------------------- 360146. End of Franson time___--____-_---___________________-_-_______-___---_ _ __ 361147. Early Tosi time___________________________________-__----_--_______________. 361148. Late Tosi time____________________.____________-___-_____----------------------------- 363

VI CONTENTS

Page FIGURE 149. Diagram showing relation between phi median diameter (Md<£) and sorting (« <£) and skewness («<£) in

Permian sandstone__________________________-_____-_-_-_--_--_---------_-_--__----__-_--- 365150-152. Graphs showing:

150. Size distribution curves of selected samples of Permian sandstone.____________________________ 366151. Change in character of size^iistribution by removal of coarse fraction________________________ 366152. Size distribution curves of sandstone and mudstone samples of the Grandeur Member of the Park

City Formation_____________________________-__-___------__----_-------------------_ 368153. Isopach map of combined Rex and Tosi Chert Members of the Phosphoria Formation__________________ 370154. Map showing thickness of apatite in the Retort Phosphatic Shale Member of the Phosphoria Formation____ 376155. Diagram showing vertical movements of Permian tectonic elements._________________________________ 381156. Isopach map of strata between the base of the Meade Peak Phosphatic Shale Member of the Phosphoria

Formation and the base of the Dinwoodv Formation.._________________________________________ 382

TABLES

Page TABLE 1. Climatic summary for southwestern Montana..__________________________________________________________ 277

2. Size parameters of sandstone from Shedhorn, Park City, Quadrant, and Phosphoria Formations of southwesternMontana__.__._________._.____._______ _________________________________________________________ 293


STRATIGRAPHY AND PETROLOGY OF THE PERMIAN ROCKS OF SOUTHWESTERN MONTANA

By EARLE E. CHESSMAN and EOGER W. SWANSON

ABSTRACT

The Permian rocks of southwestern Montana were studied as part of a broad investigation of the western phosphate field. In the southwestern part of the area studied, the Permian rocks are 600-850 feet thick and, from base to top, consist of successive layers of dolomite, phosphatic shale, chert, dolomite, phosphatic shale, and chert. The layers thin northeastward, the upper two extending the farthest. The chert and dolomite layers intertongue with sandstone to the northeast, and the chert layers in part grade into mudstone to the west. The phosphatic shale and chert layers are assigned to the Phosphoria Formation; the dolomite layers, to the Park City Formation; and the sandstone, to the Shedhorn Sandstone. Regionally, the three formations intertongue.

The Park City Formation is composed mostly of dolomite, but it includes some sandstone, mudstone, chert, and limestone. The dolomite is of three textural types: (1) aphanitic, com posed of silt-size dolomite anhedra; (2) skeletal, composed of dolomitized bryozoan and brachiopod fragments; and (3) granu lar, composed of sand-size dolomite aggregates. The aphanitic variety is the most common. The sandstone consists of fine- and very fine grained quartz sand containing a few percent of chert and feldspar grains and is cemented by dolomite or calcite. It consists of two textural types: (1) well-sorted (So about 1.26) fine-grained sandstone, and (2) less well sorted (So=1.40-1.70) fine- and very fine grained silty sandstone. The silty sandstone grades into tan dolomitic mudstone. Chert nodules and lenses are common in the dolomite, and at least some were formed by replacement.

Rocks of the phosphatic shale members of the Phosphoria Formation consist of (1) carbonate fiuorapatite in apparently isotropic or microcrystalline pellets, oolites, skeletal fragments, and nodules, (2) calcite and dolomite, (3) clay minerals and detrital quartz, and (4) carbonaceous matter. Clay minerals and quartz silt are mixed with carbonate fluorapatite in all proportions, but weakly phosphatic mudstone, highly phosphatic mudstone, and relatively pure phosphorite are more common than intermediate mixtures. The carbonate rocks in the shale members are relatively pure, and mixtures of carbonates with significant amounts of the other constituents are not common. Carbonaceous matter makes up nearly 25 percent of some beds, but less than half the beds contain more than 4 percent; it is most abundant in the mudstone and phosphatic mudstone and least abundant in carbonate rock and phosphorite.

Phosphorites are divided into those that show evidence of current action and those that do not on the basis of the pres ence or absence of a matrix and the shape, orientation, and type of apatite grain.

The bedded chert in the Rex and Tosi Members of the Phos phoria Formation is composed of microcrystalline quartz and chalcedony mixed with clay and detrital quartz. Siliceous sponge spicules from the class Demospongia form a half to two thirds of the nondetrital silica. Spicule canals are generally enlarged and filled with apatite, glauconite, or chalcedony.

The Shedhorn Standstone is composed mostly of very well sorted (So=1.09-1.24) fine- and very fine grained quartz sand stone cemented with chert, quartz overgrowths, or carbonate. The detrital fraction contains about 10 percent of chert grains and 4-8 percent of apatite pellets and skeletal fragments. Glauconite is common near the western margin of the forma tion. The nonopaque accessory detrital minerals consist mostly of zircon but include considerable amounts of tourmaline and rutile and minor amounts of garnet and apatite. The tourmaline includes several shape and color varieties and both igneous and inetamorphic types.

Principal facies changes within the Permian rocks are (1) sandstone to mudstone to dolomite, (2) sandstone to chert, (3) sandstone to chert to mudstone, (4) sandstone to dolomite, (5) sandstone to chert to dolomite, (6) chert and skeletal-oolitic phosphorite to pelletal phosphorite and mudstone to mudstone, and (7) mudstone to interbedded pelletal phosphorite and mudstone to pelletal-nodular phosphorite and mudstone.

The immediate source of the Permian sandstone was a sedi mentary terrane, as is indicated by the presence of only the most stable accessory minerals, the large number of tourmaline vari eties, and the degree of rounding of the accessory minerals. The gross distribution of the sandstone indicates one source in central Montana and another northwest of the area, perhaps near the southern end of the Bitterroot Range. The well-sorted sandstone was deposited on a wide shallow shelf at depths of less than about 30 meters. The sand was reworked by waves and benthonic organisms. The silty sandstone and the tan mudstone accumulated in deeper water.

Chert was deposited as a spicule ooze, mostly at depths of less than 50 meters. The apparently inorganic silica was pre cipitated from interstital water but was derived probably from solution of siliceous tests within the sediment. Calculations in dicate that organisms could have extracted sufficient silica from normal sea water to have formed the chert, and volcanism there fore, need not be considered as a source.

Dark mudstone of the phosphatic shale members of the Phos phoria was deposited below wave base in water containing little or no oxygen. The source of the carbonaceous matter was marine plankton. The surface water was well oxygenated, and surface circulation could not have been restricted; the bottom circulation need not have been restricted but may have been.

275

276 GEOLOGY OF PERMIAN ROCKS IN THE WESTERN PHOSPHATE FIELD

The source of phosphorus in the phosphatic mudstone and pelletal phosphorite was sea water, but it is not known whether the phosphate was extracted from sea water'by plankton or precipitated by inorganic processes. The current-washed oolitic apatite, however, was formed by inorganic precipitation around nuclei that were generally phosphatic; precipitation resulted from the increase in pH and the consequent decrease in apatite solubility when water of high P2O5 content moved upward into the zone of photosynthesis.

The facies distribution and thickness relations suggest that the main geographic elements in southwestern Montana during Permian time were a postive area in central and north-central Montana, an intermittently positive area to the west that was probably insular and perhaps in the southern Bitterroot Range, and a depositional basin that lay between the positive areas. Two cycles of transgression and regression produced the alter nating sequence of rock types. When the western positive area was submerged, cold marine currents of relatively low salinity flowed southward through the area; either chert or phosphorite was deposited, depending partly on the depth of water in the depositional basin. When the western positive area was suffi ciently high to divert the southward-flowing marine current, water in the depositional basin became warmer and more saline, and carbonates were deposited.

INTRODUCTION

PURPOSE OF INVESTIGATION

Phosphorite was first discovered in the Permian rocks of Montana near Melrose by H. S. Gale, then of the U.S. Geological Survey, in the fall of 1910 (Gale, 1911). Phosphorite deposits were subsequently investigated in many other areas in Montana, particularly north of Mel rose. The investigations included both geoglogic map ping and stratigraphic studies. Yet, at the beginning of World War II, the areal geology of large parts of western Montana was known only from broad reconnais sance, and only the gross outlines of the regional Per mian stratigraphy had been determined.

In the early days of World War II, phosphatic shale beds near Melrose that had been sampled for vanadium were found to contain small amounts of uranium. A study of the Montana phosphate deposits was therefore undertaken in 1943 and 1944 by A. P. Butler and C. W. Chesterman of the U.S. Geological Survey on behalf of the Manhattan District. These investigations were greatly expanded after the war, partly because the search for uranium was intensified but also because the rapid post-war expansion of the phosphate industry greatly increased the need for geologic information on the western phosphate deposits.

Since the start of these new investigations in 1947, stratigraphic sections of the Permian rocks have been measured and samples of the phosphatic members have been collected over nearly the entire western phosphate field. (See McKelvey, 1949, and Swanson and others, 1953, for preliminary reports on these investigations.) In addition, the geology of many hundreds of square

miles has been mapped in detail, chiefly in southwestern Montana and southeastern Idaho.

This report embodies the results of the stratigraphic and petrologic studies of the Permian rocks in that part of western Montana south of lat 46° N. Many results of the mapping program have already been released, mostly in preliminary form (Klepp'er, 1950; Swanson, 1951; Kennedy, 1949; Myers, 1952; Lowell, 1949,1953; Honkala, 1953).

PERSONNEL AND ACKNOWLEDGMENTS

Twenty-two geologists participated in measuring and sampling the Permian rocks of southwestern Mon tana during the field studies on which this report is based, and their contributions are acknowledged in the descriptions of sections on pages 384-561. The field studies of M. R. Klepper, W. R. Lowell, F. S. Honkala, and J. A. Peterson are particularly noteworthy. We also gratefully acknowledge the many contributions that have been made to this report by our colleagues, particularly V. E. McKelvey, who organized and guided the program, and T. M. Cheney, R. P. Sheldon, R. A. Gulbrandsen, and L. D. Carswell. All these men have studied the Permian rocks in other parts of the western phosphate field.

The investigation has been conducted as part of the Department of the Interior program for the Missouri River basin and has been supported partly by the Di vision of Raw Materials of the U.S. Atomic Energy Commission.

GEOGRAPHY

Southwestern Montana is characterized by mountain masses separated by wide intermontane basins (pi. 14). The Centennial Mountains, which extend westward from Yellowstone National Park along the Idaho-Mon tana State line, trend eastward, but most of the other ranges trend northward. A few peaks in the larger ranges exceed an altitude of 10,000 feet above sea level, and Koch Peak in the Madison Range, the highest point in the area, is 11,293 feet above sea level. The intermontane basins decrease in general altitude from south to north; Centennial Valley is nearly 7,000 feet above sea level, whereas Three Forks Basin ranges from 4,000 to 5,000 feet in altitude.

Most of southwestern Montana is drained by head waters of the Missouri River; the western two-thirds is drained by the Jefferson River and its tributaries the Big Hole, Beaverhead, and Ruby Rivers and the eastern third, by the Madison and Gallatin Rivers. The parts of Idaho included in the area discussed in this report drain to the Pacific by way of either the Salmon or the Snake Rivers.

STRATIGRAPHY AND PETROLOGY, PERMIAN ROCKS OF SOUTHWESTERN MONTANA 277

TABLE 1. Climatic summary for southwestern Montana

[From U.S. Dept. of Agriculture Yearbook, 1941J

Station

Dillon Lima Hebgen Dam

Three Forks Ennis Virginia City

Temperature (°F)

Length of record (years)January average.July average. _MaximumMinimum

3924.4CC 1

98-40

1Q16.362.9

100-43

3511.759. 599

-60

1421. 366.9

101-49

2121.764. 5

100-43

2920. 366. 1

103-43

Average dates of killing frosts

Length of record (years) _Last in springFirst in fallGrowing season (days)

39May 22Sept. 12

113

16

Sept. 687

35

Sept. 1188

16May 30Sept. 19

112

21June 2Sept. 11

101

29May 30Sept. 18

111

Average monthly precipitation (inches)

Length of record (years)January _FebruaryMarch__April.MayJuneJuly._________________ ______AugustSeptember _October __ _ _November __ _ _ _December. _ _ __

Average annual

40on

. 801.271.802.712.431 4Q1. 301.37

QK.82.80

16.67

19262749

1 201 211 67

997686963624

9.27

342.651.931.971. 572.092. 161.831. 401. 531. 781.812. 12

22. 84

19.40. 39.42

1.031.732.091.40.96

1.34.92.63. 55

11.86

20.53.49.67.96

1. 431.711. 171.04.95.89.44.41

10. 69

28.64.46.86

1. 181.901. 781.281.201.27.99.80.62

12.98

Pertinent climatic data are listed in table 1. The winters are long and severe and the summers are short and mild. Precipitation is light, averaging 9-23 inches in the valleys and somewhat more in the mountains; nearly a third of it falls in May and June. The aver age annual snowfall for the period from 1899 to 1938 ranged from 60 to more than 100 inches in different parts of the area, and the average duration of snow cover during the same period ranged from 120 to more than 160 days (U.S. Department of Agriculture, 1941, p. 727, 728); both the snowfall and the duration of snow cover are, of course, greater in the mountains.

The area is crossed by several paved highways, and in dry weather most of the back country is accessible by means of gravel and dirt roads. Most of the principal towns are connected by rail.

GEOLOGIC SETTING

The Paleozoic strata of southwestern Montana consist of shallow-water marine rocks that thicken from about 3,000 feet near Yellowstone National Park to about 7,000 feet near the 113th meridian. Most of the Pale

ozoic rocks are composed of limestone and dolomite but include several prominent units of quartz sandstone and shale; the thickest and most extensive sandstone is the Quadrant Formation of Pennsylvanian age, which directly underlies the Permian rocks. The Paleozoic beds were deposited on a slightly unstable cratonic shelf; the shelf was separated from the Rocky Mountain miogeosyncline to the west by a hinge zone that fluctu ated between the present Lemhi Range and Tendoy Mountains (Scholten, 1957, p. 168). The hinge zone was uplifted sometime prior to the Middle Ordovician, in the Devonian, during the Early and Middle Missis- sippian, and probably during part of the Permian (Scholten, 1957, p. 169; 1960).

Lower Triassic rocks consist of marine shale, lime stone, and sandstone. They are nearly 2,000 feet thick in the southern part of the area, but they thin abruptly northward and pinch out south of the Jefferson River. They may originally have extended as far north as lat 36° K (McKee and others, 1959, pi. 9).

Sometime between Early Triassic and Middle Juras sic time, central Montana was broadly uplifted and


eroded. Several hundred feet of marine and continen tal Middle and Upper Jurassic beds were then deposited across the truncated older rocks. As a result, Jurassic beds rest on the Mississippian in north-central Montana and on progressively younger beds to the west, south, and east (McKee and others, 1956, pi. 2). The Jurassic rests unconformably on the Permian in the Three Forks area, but elsewhere in the report area, it rests uncon formably on the Lower Triassic.

The Cretaceous rocks consist of salt-and-pepper sand stone, siltstone, and shale and contain much volcanic debris. The section may in places exceed 9,000 feet in thickness (Reeside, 1944). The detritus was derived from a rising landmassto the west.

In Late Cretaceous and early Tertiary time, the pre- Cenozoic rocks were deformed by the Laramide orogeny. West of the Beaverhead River the folds that resulted are tight, and the rocks have been thrust eastward along several low-angle faults; but east of the river the folds are generally open and are broken by high-angle re verse faults and local thrusts. The difference in the character of deformation in these two parts of the area is reflected in the outcrop pattern of the Permian rocks (fig. 6), which in the western third of the area is con siderably more sinuous and complex than in the eastern two-thirds. The greater crustal shortening west of the Beaverhead River should be borne in mind when the isopach and facies maps of the Permian rocks are interpreted.

The present ranges and basins of southwestern Mon tana were formed by crustal movements that began as early as the Oligocene (Pardee, 1950, p. 366). The ranges result mostly from faultblock uplift, and Recent fault scarps may be seen along the front of several ranges. The intermontane basins contain thick ac cumulations of highly tuffaceous fine-grained water-laid sediments of Tertiary age that conceal the bedrock over large parts of the area.

METHODS OF STUDY

Fimj> PROCEDURES

The Permian rocks in southwestern Montana are mostly relatively resistant sandstone, dolomite, and chert; the important phosphorite beds, however, occur in two nonresistant shale members that generally do not crop out. In the present investigation the shale members were exposed by trenching with bulldozers wherever possible (figs. 87 and 88) and by hand trenching where the members were too thin or too inac cessible to be reached by bulldozer. Sites for trenching were selected generally on steep slopes where float from the shale members was abundant and relatively un- mixed with foreign material and where mapping and reconnaissance indicated no structural complications.

FIGURE 87. Bulldozer trench at Sheep Creek, locality 1234, where the entire Permian section was exposed by trenching. This is the type locality of the Retort Phosphatic Shale Member of the Phosphoria Formation. Beds dip 30°-40° toward the viewer.

Wherever possible, the entire Permian section was measured, but the shale members were described in more detail because of their economic importance. Within the shale members, distinct lithologic units thicker than 0.1 foot were described separately unless they were a part of a uniformly interbedded sequence. Hand speci mens were collected from every described unit, and channel samples were taken from every unit thicker than 0.5 foot. Beds less than 0.5 foot thick were grouped with adjacent beds to form sampling units of suitable thickness. The maximum thickness of sampled units in the shale member was 5.0 feet, and the average thickness was between 1 and 2 feet. The minimum weight of channel samples was 12 pounds, but where trenches were accessible to vehicles, samples as heavy as 80 pounds were collected.

Channel samples were collected from the nonphosphatic parts of the section at only a few localities, but

FIGURE 88. Retort Phosphatic Shale Member of the Phosphoria Forma tion exposed in bulldozer trench at Greenstone Gulch, locality 1250, Note depth of zone of creep.


hand specimens were taken from every described bed in every section.

Each measured section was assigned a lot number; each measured bed, a unit number; and each channel sample, a sample number. The lot numbers and sample numbers used in this report are those originally as signed, but the units have been renumbered starting with 1 at the base of each section and continuing con secutively up section. The unit numbers are prefaced with letters that designate the stratigraphic member of which unit is a part.

In order to standardize the measurement and field de scription of the beds by the many geologists participat ing in the fieldwork, forms were used that contained spaces in which to record unit number, sample number, rock name, unit thickness, texture, grain size, hardness, thickness of bedding, color, jointing, nature of contact with the underlying unit, and the presence of fossils. An explanatory text by V. E. McKelvey described the use of the form and denned terms to be used. Colors were determined by comparison with the "Bock-color Chart" distributed by the National Eesearch Council (Goddard, 1948), supplemented by a specially prepared chart, in which the Munsell system was also used, that covered in detail the range of colors most common in the shale members.

Fossils were systematically collected from most of the sections that were measured.

LABORATORY PROCEDURES

TREATMENT Or CHANNEL SAMPLES

All channel samples were shipped to Montpelier, Idaho, where they were crushed to minus i/^-inch mesh and reduced to 10 pounds by use of a combination jaw crusher and Vezin-type splitter (Huleatt, 1950). The 10-pound samples were sent to the U.S. Geological Survey laboratory at Denver, Colorado, where they were split into two parts, one of which was stored for future reference as needed. The other split was ground to minus 20 mesh, from which two 4-ounce splits were cut and ground to minus 80 mesh. One minus-80-mesh split was sent to the U.S. Bureau of Mines laboratory at Albany, Oreg., where it was analyzed for P2O5 and acid-insoluble content; the other was sent to the U.S. Geological Survey laboratory in Washington, D.C., where it was analyzed radiometrically for uranium. If a split showed a content of 0.005 percent equivalent uranium, it was analyzed chemically for uranium. Many of the samples were also analyzed for A12O3 , Fe2O3 , and loss on ignition, some by the Washington laboratory of the U.S. Geological Survey and some by the Albany, Oreg., laboratory of the U.S. Bureau of Mines. A few samples were analyzed chemically for

Fluorine and V2O5, and some were analyzed spectro- graphically for a large number of elements by the U.S. Bureau of Mines laboratory, Albany, and the U.S. Geo logical Survey laboratory, Washington, D.C. Determi nations of carbonaceous matter were made on several hundred samples of the black-shale units mostly by the Washington laboratory, but some were made by Bond Taber of the U.S. Geological Survey at Menlo Park, Calif.

CHEMICAL ANALYSES

P2<>5

A 0.3000-gram sample was treated with a mixture of 5 milliliters concentrated HNO3 , 5 milliliters HC1, and 8 milliliters concentrated HC1O4. After filtration, P2O5 was precipitated by (NH4 ) 2MoO4 at 65° C, and the precipitate was dissolved in an excess of standard NaOH; the excess NaOH was then titrated with stand ard HNO3 .

Two hundred samples of phosphatic rocks from all parts of the western phosphate field that had been ana lyzed by the U.S. Bureau of Mines laboratory at Albany, Oreg., were subsequently analyzed by the U.S. Geo logical Survey laboratory at Washington, D.C. Eighty percent of the duplicate analyses differed from the orig inal by less than 1.3 percentage points; 90 percent, by less than 2.0 percentage points; and 95 percent, by less than 2.5 percentage points. Although comparison of these analyses does not afford a statistically correct measure of either accuracy or precision, it does demon strate that the analyses are sufficiently reliable for the purposes for which they have been used in this report.

Gross errors were detected by comparing the analyses with the mineralogic composition of the hand specimens and the powder splits, and the samples were reanalyzed as necessary. The errors were not necessarily analytical but may have originated in the labeling of samples, in bookkeeping, or in copying of results.

The phosphorus in the Permian rocks of Montana, as in most marine apatites, is in the mineral carbonate- fluorapatite (Altschuler and Cisney, 1952), which in these rocks probably has a composition of (Ca, Na, Sr, U)io(P, Si, S) 6_X (0,F) 24_ 3X (C03 ) XF2 (Gulbrandsen, 1960) - 1 The extent of substitution, and thus the exact composition, is not known. It is assumed in this report that carbonate-fluorapatite contains approximately 39 percent P2O5 and that the P2O5 content can be con verted to apatite content by multiplying by 2.56. Be cause of the large number of substitutions possible in

1 Gulbrandsen (1960a) discussed the applicability of the terms "cello phane" and "francolite" to the apatite variety present in the Phosphoria Formation and concluded that their use is not justified. The usage in this paper follows Gulbrandsen's recommendation in calling the phos phate mineral carbonate-fluorapatite or simply apatite where it is the only phosphate mineral of reference.


the apatite lattice, the conversion factor 2.56 is only an approximation.

ACID INSOLUBLE

The part of the 0.3000-gram sample that was insolu ble in the mixture of HNO8 , HC1, and HC1O4 was washed with water, ignited at 1,000° C for 1 hour, cooled, and weighed.

Ninety-nine samples that had originally been ana lyzed at the Albany laboratory of the U.S. Bureau of Mines were reanalyzed at the same laboratory. The acid-insoluble analyses of 49 of the samples differed by less than 1 percentage point and of 84, by less than 2 percentage points. The mean value of the reanalyses, however, differed by about 1 percentage point from the mean of the original analyses. The results cannot be applied to the acid-insoluble analyses as a whole, but they indicate that any lack of precision in the determi nations is unimportant for most purposes.

The acid-insoluble analyses are an approximation of the total quartz and silicates. They are minimum val ues, for silicates soluble under the conditions of the analyses may constitute several percent of the total quartz and silicates of the more argillaceous samples.

UBANIUM

All samples were analyzed radiometrically for ura nium, and those that contained more than 0.005 percent equivalent uranium were then analyzed fluorimetrically.

Fluorimetric uranium values determined prior to 1949 are consistently low, and the radiometric determina tions for those years are a more reliable indication of the actual uranium content (Z. S. Altschuler and F. S. Grimaldi, written communication, 1951).

Some measure of the precision of uranium analyses of samples collected in 1949 and subsequent years is given in figure 89, in which the original analyses of 22 samples collected in 1949 are compared with repeat analyses of the same samples made 5 years later. The samples were chosen at random from among all phosphatic samples collected in 1949 in the western phos phate field.

CARBONACEOUS MATTER

The sample was heated to constant weight at 230° C and again to constant weight at 450° C. The percent carbonaceous matter equals the difference in weights at the two temperatures divided by the weight of the sam ple and multiplied by 100 (Grimaldi in Thompson, 1953).

No rigorous test of the reliability of the carbonaceous- matter determinations has been made, but nine samples were analyzed at different times by two different ana lysts. Five of the nine samples differed by less than 1

percentage point; seven, by less than 2 percentage points; and eight, by less than 3 percentage points.

SPECTBOGRAPHIC ANALYSES

Kesults of the semiquantitative spectrographic anal yses are based on comparisons with a standard plate representing known quantities of the elements tested for and made at the same exposures. The standard sensi tivities for the elements noted in this report are as follows:Element Percent

Al ______________ 0. 005SbAsBaBeBiB _CdOaOrCoOuGaGeAuFePb

,051

,08,001,002,001,1,01,02,01,001,05,01,01,005,1,2

Element

Mg_Mn _ Mo_NiNb _ _PPtSiAg _____ NaSrTaSn __ - TiW - V __ - -Zn _ Zr _ -

Percent

_ _ 0.001.004

_ _ __ .004_ _ _ .01

___ __ .01__ _ _ .8

__ _ .01.002

_ __ . 001_ _ _ .05

.1_ _ 1.0

.01_ _ .002

_ _ _ .1_ _ .01

____ __ . 05_ __ .003

OTHER ANALYSES

Loss on ignition was determined by igniting the sam ple at 1,000°C. The mineralogical significance of the value obtained is uncertain, but the loss on ignition in cludes chiefly carbonate CO2 , carbonaceous matter, water, and sulfur.

Total iron is reported as Fe2O3 . Most of the iron occurs in limonite, pyrite, or glauconite.

Aluminum was precipitated and weighed as alumi num phosphate but reported as A1 2O3 . Nearly all the aluminum occurs in the clay minerals, but some is pres ent in glauconite and feldspars.

Most of the fluorine reported occurs in carbonate- fluorapatite, but fluorite has been noted in some beds.

PETROGRAPHIC METHODS

EXAMINATION OF HAND SPECIMENS

Nearly all hand specimens collected in the field were examined in the laboratory under the binocular micro scope ; approximately half of these specimens were also powdered and examined in oils under the petrographic microscope, generally in order to determine the amount and type of carbonate minerals.

THIN SECTIONS

More than 400 thin sections were studied. The quan tities of constituents were generally estimated, but esti-


25

o 20

XID

H

LUO

LU 15

10

Chemical

r =0.906 S.,* =1.84

Radiometric

r= 0.937 S, x =1.27

10 15 25 25 0 5

= RERUN ANALYSIS, IN PERCENT U X 10 3

10 15 20 25

FIGURE 89. Comparison of original and rerun uranium analyses of 22 samples of phosphorite collected in 1949; r is correlation coefficient,Sy.x is standard error of the mean.

mates of about 20 of the specimens were checked by point counts.

SIZE ANALYSES

Sieve analyses produced poor results. Much, of the sandstone is only moderately well cemented and was disaggregated with little difficulty to pass 60 mesh, but enough small groups of grains were so tightly cemented that most of the material retained on the 60-, 70-, and 80-mesh screens consisted of aggregates. Furthermore, apatite and glauconite grains were crushed during disaggregation and concentrated in the finer sizes, and chert cement broke into angular fragments that were present in all size fractions. We therefore resorted to thin-section size analyses.

The thin-section size analyses were made by means of a micrometer ocular and a point counter; the short axis of the grain at each point was measured and tallied in the appropriate ^-phi class. Only detrital grains were counted. This procedure yielded a volume-per cent distribution which, because of the similar specific gravities of nearly all the grains counted, closely ap proximated a weight-percent distribution.

The values for several of the thin-section size distribu tions were corrected for the effect of sectioning by the method of Packham (1955). In general, correcting the distribution value increased the median-diameter value by ^-phi unit or less and decreased the sorting coeffi cient (/So) by less than 0.1 and generally by less than 0.05. Unfortunately, the corrected size-distribution curves of several of the specimens exceeded 100 per

cent. For pictorial representation and for comparison between samples, therefore, the uncorrected thin-section data have been used, but values for the corrected dis tributions have been used for comparison with pipette- analyses data and with sieve data of other investigations. We do not know how close the corrected distribution would match the distribution of the unconsolidated sand, but the Packham correction method at least changes the value for the distribution in the proper direction. Size-distribution curves constructed from the sieve data and the uncorrected and corrected thin- section data for one sample are compared in figure 90.

Pipette analyses were made of several mudstone samples. The samples were ground to minus 80 mesh and soaked for several months in distilled water to which a few milliliters of ammonium hydroxide had been added. The samples were shaken intermittently.

HEAVY-MINERAL SEPARATION

Heavy minerals were separated by centrifuging in bromof orm having a specific gravity of 2.58. Limonite stains were removed before centrifuging by heating the sample in 2-percent hydrochloric acid for half an hour. Separations were made into the following size fractions: 0.044-0.062 mm, 0.062-0.088 mm, 0.088-0.125 mm, and 0.125-0.177 mm.

X-RAY

X-ray diffraction patterns of 30 bulk samples from the shale members were made by Bond Taber of the U.S. Geological Survey in order to identify the carbon-

282

120

100

CUMULATIVE PERCENT

r>o J> <r> oo o o o o

0

GEOLOGY OF PERMIAN ROCKS I

) 1

I

1

/ril1 1' ! 1 I?/ ///

~^J/

/*\/ V'» \ / \/ '

/,' >

,' /? //-' ' rI /I'<

/I 1 /Thir// rx/ /' ' X/ < x ";I'//F "i

' / Sieve ' / Thin sectic

/ Thinsectio

/

^Corrected thin s

Sievet^x-^ '

i section

Md^ 3.05

n 3.38 n, corrected 3.22

ection

<

A^<y So 0.120 1.24 0.096 1.22 0.107 1.15

DIAMETER, IN PHI

FIGURE 90. Comparison of sieve and thin-section size analyses ; sample Us-124, lot 1234. Md<t>, phi-median diameter; Md, median diameter (mm) ; So, Trask sorting coefficient.

ate minerals, determine the gross mineralogy of the clay fraction, and detect feldspar and gypsum.

TERMINOLOGY

Color. The color names and numerical designations are those of the Munsell color system.

Hardness. If a rock did not break under a single sharp blow of the hammer it was termed "hard"; if it did break, it was termed "medium hard"; but if it crumbled or retained an imprint of the hammer head, it was termed "soft." The terms "crumbly," "plastic," and "brittle" were used if appropriate.

Thickness of bedding. Thickness of bedding as used in this report might more appropriately have been called thickness of splitting on weathering; it refers to the thickness of layers between visible cracks parallel to stratification. The quantitative terms are defined asfollows: Feet

Very thick bedded_______________ >1. 0 Thick-bedded _________________ 0. 2-1. 0 Thin-bedded __________________0. 02-0. 2 Fissile ______________________ <0.02

Rock terms. Definition of the rock terms are as fol lows (the adjective forms are in parentheses) :

Phosphorite (phosphatic): A rock composed dominantly of carbonate-fluorapatite; rocks containing more than 19.5 percent P2Os are phosphorites, and rocks containing more than 7.8 percent P2O5 are phosphatic.

Limestone (calcareous): A rock composed dominantly of calcite.

Dolomite (dolomitic): A rock composed dominantly of the mineral dolomite.

Carbonate rock (carbonatic): A rock composed, dominantly of a mixture of calcite and dolomite, or one composed domi nantly of carbonate minerals, the identity of which is not known.

Sandstone (sandy): A rock composed dominantly of detrital quartz and silicates having a modal grain size between 0.062 and 2.0 mm. Nearly all the detrital grains in the sandstone discussed in this report consist of quartz and chert, and all the sandstone belongs to the quartzite series of Krynine (1948, p. 149).

Mudstone (muddy): A rock composed dominantly of detrital quartz and silicate having a modal grain size of less than 0.062 mm. If the modal grain size is between 0.004 and 0.062 mm, the rock is a siltstone (silty) ; if the modal size is less than 0.004 mm, it is a claystone (clayey). In practice, the difficulty in determining grain size in the finer grained rocks has resulted in classifying most of them as mudstone.

Chert (cherty): A rock composed dominantly of nondetrital quartz and chalcedony. The adjective "cherty" is used only if the authigenic quartz and chalcedony are evenly distributed through a rock; it is not applied to a rock containing chert nodules.

Oolite (oolitic) : A constructional particle 0.062-0.2 mm in diameter having a concentric structure.

Pellet (pelletal) : A constructional particle 0.062-0.2 mm in diameter having no regular internal structure.

Nodule (nodular) : A constructional particle larger than 2 mm in diameter.

Skeletal fragment (skeletal): A particle consisting of the hard part of an organism; where used as part of a rock name, it refers only to particles between 0.062 and 2 mm in diameter.

Grain (granular): Where used as part of a rock name, a particle between 0.062 and 2 mm in diameter.

The grade scale used is that of Wentworth (1922), and the size terms "very coarse," "coarse," "medium fine," and "very fine" have the same grade limits when applied to phosphorite and carbonate rock as they do when applied to sandstone. For example, a finely pel letal phosphorite consists of apatite pellets having a modal diameter between 0.125 and 0.250 mm. Phos phorite and carbonate rock in which the constituent grains are of silt or clay size are described as aphanitic.

EXPLANATION OF ILLUSTRATIONS

The outcrops of Permian rocks and the exact location of each measured section and partial section are shown in relation to the land net in plate 15. The relations of the localities of measured sections to major geo graphic features are shown in plate 14, in which the locations of the sections are identical with those given~


in plate 15, except for several where the complete section has been pieced from several lots or where one of several closely spaced sections has been chosen to represent the area. The locations, lot numbers, and locality names in plate 14 are those used throughout the text of the report.

The lithology and correlation of the Grandeur Member of the Park City Formation are shown in plates 16 and 17, and similar information on the rest of the Permian section is shown in plates 18-22. Correla tions within the Retort Phosphatic Shale Member of the Phosphoria Formation are shown in more detail in plates 23 and 24.

Maps showing the areal variations of lithologic char acter have been constructed by a method devised by Pelto (1954, p. 503-505), in which the variation of any number of components is mapped as a single func tion. In constructing the maps, the rocks are divided into classes, each of which contains a unique end mem ber consisting of either a single component (such as sand or carbonate) or a mixture of simple type (such as equal amounts of sand and carbonate). These classes are designated class I if the end member is a single component, class II if the end member is a mixture of two components, class III if the end member is a mix ture of three components, and so on. A variable quan tity D expresses variations in composition within each class; the minimum value of D is that of the end mem ber, and the maximum value, 100, is that at the class boundary. In the maps in this paper, the component is generally a single constituent rather than a rock type;

for example, all the sand in the mapped unit constitutes the component rather than all the sandstone.

To calculate the D function, the proportions of the components are arranged in order of increasing magni tude from left to right, and zero is added to the left of the smallest component. Positive differences are taken between adjacent components and are labeled from right to left as (Ap)i, (Ap) n, and so on. The class number is denoted by the subscript of the largest (A^>). The largest (A^>) is then denoted as (A^?) TO and the next largest as (Ap) vm. The D function is then defined as:

Z>=100 (l-[Ap) m -(Ap) cm ]).

For example, consider a rock unit containing 42 percent quartz sand, 40 percent dolomite, 15 percent clay, and 3 percent apatite. The calculation is as follows:

Apatite 0.03

Clay 0.15

Dolomite 0.40

Sand 0.42

Subtracting adjacent numbers and labeling the differ ences from right to left, we obtain:

(Ap)iv 0.03

(Ap)m 0.12

(Ap)n 0.25 0.02

The class number is II; that is, the rock is a nearly equal mixture of two components. Continuing,

EXPLANATION

D=100 (1-(0.25-0.12)) =87

The D function is contoured in only a few of the maps, as the density of control in the remaining maps was insufficient.

Figure 91 illustrates the relation of the class areas and the D value to composition in a three-component system.

Chert

Class I area Class II area Class in area

Sand Sand and carbonate Sand, chert,and carbonate

Carbonate Chert and carbonate

80 Contour of £> value

Contour interval 2O units

Sand

-:-:-:-:-x-:^-^:-:-:£-:-:-:-:-:*:-:^

Carbonate

FIGURE 91. Relation of class areas and D values to composition in a three-component system. Modified from Pelto (1954, fig. 2).


STRATIGRAPHY AND PETROGRAPHY

STBATIGBAPHIC NOMENCLATURE

HISTORY OF NOMENCLATURE

The Permian section of southwestern Montana is com posed of four major rock types chert, dolomite, sand stone, and interbedded phosphorite and dark mudstone. Just east of Lima, Mont., where the interval is about 600 feet thick (fig. 92), a three-member sequence of dolomite, phosphatic shale, and chert is repeated twice from bottom to top. The layers thin toward the north east, and the upper two layers extend farther eastward than the rest of the sequence; the chert and dolomite layers intertongue with sandstone to the northeast, and the chert layers in part grade into mudstone to the

west. These changes in both character and thickness of the individual layers cause the gross aspect of the Permian to differ in various parts of southwestern Mon tana. West and south of Dillon the Permian is com posed dominantly of chert and mudstone; near Melrose it is composed dominantly of dolomite; and near Yel- lowstone National Park it is composed dominantly of sandstone.

Before 1910, when phosphate-bearing beds were first recognized in Montana, the more resistant beds of the~ '

sequence were grouped either with the underlying beds in the Quadrant Formation (Peale, 1893, p. 41-43, and 1896; Iddings and Weed, 1894) or with the overlying beds as the Teton Formation (Hague and others, 1896,

112° 111°

MONTANA "/^WYOMING

FIGURE 92. Isopach map of Permian rocks in southwestern Montana. X. control point; figure shows measured thickness, in feet.


and 1899, p. 34). In reporting the first discovery of phosphorite in the Permian of Montana, Gale (1911) did not assign a formational name to the phosphatic interval and the related rocks but referred to them as "beds of Pennsylvanian age which overlie the Quadrant formation." In 1913, Emmons and Calkins in dis cussing the stratigraphy of the Philipsburg quadrangle, included the phosphate-bearing beds and the overlying chert and quartzite in the Quadrant, but they quoted Gale on the probable correlation of these beds with the Park City Formation of Utah and southeastern Idaho (Emmons and Calkins, 1913, p. 72-74). Pardee (1913) followed the same usage in reporting his dis covery of phosphorite in 1911 in the Garnet Range.

The name Phosphoria, the type area of which is in southeastern Idaho, was first applied to Permian rocks in Montana by Stone and Bonine (1914, p. 375), who applied it to the thin Permian section of phosphorite, chert, and sandstone in the Elliston region, about 20 miles west of Helena, From 1911 to 1956, with the ex ception of the Philipsburg area (Calkins and Emmons, 1915, p. 8), the mapping of which had already been completed, the Permian rocks of western Montana were assigned to the Phosphoria.

During most of the investigation for this report, the name Phosphoria was retained for all the rocks between the massive Quadrant Quartzite and the Mesozoic for mations. The Phosphoria itself was divided into five units, from oldest to youngest, the A, B, C, D, and E members. The B and D members are the two phosphatic shale units; the A member, the basal dolomite unit; the C member, a chert, dolomite, and sandstone unit; and the E member, the uppermost chert and sandstone unit. This terminology was first used in 1945 by A. P. Butler and C. W. Chesterman and first published in summary by McKelvey (1949). Klepper (1950) first described these members in detail. The terminology has been fol lowed in all preliminary reports published during the present investigation. (For example, see Cressman, 1955.)

CURRENT NOMENCLATURE

In the nomenclature recently adopted by the U.S. Geological Survey for the western phosphate field (Mc Kelvey and others, 1956 and 1959), an attempt has been made to give some lithologic significance to the forma tional names by (1) restricting the name Phosphoria to the phosphorite, dark-mudstone, and chert facies, (2) restricting Park City to the limestone and dolomite facies, and (3) introducing a new name, Shedhorn Sandstone, for the sandstone facies in Yellowstone Na tional Park and adjacent areas. Relations between facies are expressed in terms of intertonguing; thus, the Park City Formation in the Wasatch Mountains of

709-931 O 63 2

Utah consists of two members separated by a tongue of the Phosphoria Formation, and the Phosphoria in ex treme western Wyoming consists of two parts separated by a tongue of the Park City Formation. The forma tions are subdivided into members, and the member names are extended as far as the units retain their litho logic character. Thus, the Meade Peak Phosphatic Shale Member of the Phosphoria Formation of south eastern Idaho extends into the Wasatch and Uinta Mountains of Utah and into the Yellowstone National Park area of Wyoming as the Meade Peak Phosphatic Shale Tongue of the Phosphoria Formation. Figure 93 illustrates the resulting formational and member nomenclature. Locality 4 shown on figure 93 is near the type section of the Shedhorn Sandstone; locality 6 is near that of the Phosphoria Formation; and locality 7 is near that of the Park City Formation.

The stratigraphic nomenclature of the Permian in southwestern Montana is shown in detail in plates 16-22. The units present are as follows: (1) The Park City Formation, consisting of the Grandeur and Franson Members; (2) the Phosphoria Formation, consisting of the Meade Peak and Retort Phosphatic Shale Members, the Rex and Tosi Chert Members, and the cherty shale member; and (3) the Shedhorn Sandstone, consisting of an upper and a lower member.

The success of the nomenclature in reflecting the litho logic character of the interval may be judged by com paring figure 94, which shows the lithologic character of the Permian rocks, with figure 95, which shows the constitution of the Permian section by formations. Al though the agreement between the two figures is good, better agreement is prevented by the lithologic variation within the Park City Formation. Both the Grandeur and Franson Members contain terrigenous material in the western part of the area that locally makes up most of the formation. To separate these beds from the Park City and raise them to formational rank would be con sistent with the nomenclature adopted for the Permian rocks, but the area in which they are known to crop out is too small to justify such action now.

Although the stratigraphic nomenclature adopted for these rocks reflects more closely their lithologic char acter and conforms more closely to the recommendations of the American Commission on Stratigraphic Nomen clature (1961) than did the earlier nomenclature, its application does present some difficulties. First, in areas where intertongumg is complex, the nomenclature is correspondingly complex. Complex nomenclature in such an area is very meaningful to a geologist studying regional stratigraphy, but it is a nuisance to the geolo gist mapping a restricted area. Second, the tongues cannot be traced continuously in outcrop but must be


EXPLANATION

Hiatus

t HELENA

MONTANA

IDAHO | -Jacksoli

6| WYOMING6Montpelier^

RADO UTAH

100 200 MILES

FIGURE 93. Nomenclature of the Phosphoria, Park City, and Shedhorn Formations. 'Modified from McKelvey and others (1956, fig. 4).

correlated from section to section across areas of no exposure; therefore, the nomenclature reflects in part our confidence or in part lack of confidence in the correlation.

The second point is illustrated by differences of opin ion between the authors. Swanson would, in general, prefer to extend formation and member names farther than Cressman. For example, at Big Sheep Canyon and Dalys Spur, Swanson would assign sandstone that is herein included in the Franson Member of the Park City Formation (p. 288) to the Shedhorn Sandstone, and at Indian Creek he would formally recognize chert beds that are herein included in the lower member of the Shedhorn Sandstone as tongues of the Rex Chert Mem ber of the Phosphoria Formation.

PARK CITY FORMATION

GENERAL, CHARACTER AND DISTRIBUTION

The type area of the Park City Formation is Big Cottonwood Canyon near Salt Lake City, Utah, where the formation consists of a lower and an upper mem ber, each composed of limestone and dolomite contain ing some interbedded sandstone; the members are sep arated by the Meade Peak Phosphatic Shale Tongue of the Phosphoria Formation. Cheney (in McKelvey and others, 1956, p. 2840, 2842-2843) named the upper unit the Franson Member and the lower unit the Grandeur Member (Cheney in McKelvey and others, 1959, p. 36) ; he applied the names to beds that extend northward through western Wyoming and into Montana. In southwestern Montana the-Park City Formation com-


113°

Permian rocks disconformably overlain by Ellis Group (Jurassic) north of line

ONTANA WTOMING

Permian rocks disconformably overlain Dinwoody Formation (Triassic) east of line

EXPLANATION

Sand Chert Mud Carbonate Conglomerate

Pattern used singly where one constituent is dominant (class I areas); combined where 2 or 3 constituents are dominant (class I and Mareas)

FIGURE 94. Lithologic character of the Permian rocks in southwestern Montana. 'X, control point; A, control point, data approximate.

prises the strata, dominantly dolomite but in a few lo calities mostly sandstone and siltstone, that are under lain by the massive well-sorted quartz sandstone of the Quadrant Formation of Pemisylvanian age and that are overlain by the phosphorite and dark mudstone of the Eetort Phosphatic Shale Member of the Phos- phoria Formation. In the southwestern part of the re port area, the Grandeur and Franson Members of the

Park City Formation are separated by the Meade Peak and fvex Tongues of the Phosphoria Formation. These tongues of the Phosphoria pinch out to the northeast, and where they are absent, the Grandeur and Franson Members cannot be readily distinguished from each other. Carbonate rock of the Park City Formation intertongues in part with sandstone both to the east and west. The sandstone to the east is assigned to the


ill 0

Permian rocks disconformably overlain by Ellis Group (Jurassic) north of line

Permian rocks disconformably overlain byDinwoody Formation (Triassic) east of line

EXPLANATION

Patterns used singly where one formation is dominant (class I areas); combined where 2 or 3 formations are dominant (class U and HI areas)

FIGURE 95. Constitution of the Permian of southwestern Montana, by formations. X, control point; A, control point, data approximate.

Shedhorn Sandstone, but that to the west, as well as the associated dolomitic mudstone, is included in the Park City because it cannot be demonstrated to be con tinuous with the Shedhorn of the type area.

The distribution and thickness of the Park City For mation in southwestern Montana are illustrated in fig ure 96, and the lithologic character of the information

is indicated in figure 97. In both illustrations, tongues of other formations have been excluded. The eastern edge of the Park City Formation is in the vicinity of the Gallatin River; the formation thickens southwestward and reaches a maximum of about 600 feet at Haw- ley Creek on the western side of the Beaverhead Range. The general thickening trend is interrupted by thinning

STRATIGRAPHY AND PETROLOGY, PERMIAN ROCKS OF SOUTHWESTERN MONTANA

113° 112° 111°

289

FIGURE 96. Isopach map of the Park City Formation. X, control point showing measured thickness in feet; A, control point data approximate.

along a line northwestward through Wadhams Spring. The dominance of carbonate rock in the Park City is well indicated in figure 97. Sandstone makes up most of the formation in a relatively small area west of Dillon.

LITHOLOGY

CARBONATE ROCK

The typical carbonate rock of the Park City Forma tion in Montana is a hard light-colored aphanitic dolo mite of low chroma. Dolomite greatly predominates over limestone and constitutes more than 95 percent of the total carbonate rock at most localities.

Most of the carbonate rock in the Park City Forma tion ranges in color from medium and light gray to yellowish gray and pale brown. The hues range from 5Y to 10 TR (with the exception of a very few red-hued beds), but in rocks of such low chroma the recorded dif ferences in hue are not very significant. In general, the color of all the carbonate rocks within a member at a given locality is rather consistent. At Big Sheep Canyon, for example, 27 of 28 dolomite beds in the Grandeur Member have values of 5 and 6, and 10 of 13 beds in the Franson Member have values of 7 or greater.

The dolomite of the Grandeur Member of the Park City is thin bedded in the southwest part of the area but


EXPLANATION

Sand Chert Carb Patterns used singly in class I areas; combined in

class H and HI areas

50

Isopleth of D valuesContour interval 25 units

FIGURE 97. Llthologic character of the Park City Formation. X, control point (numeral is value of D function) ; A, control point, dataapproximate.

is thick bedded in the eastern and northern parts. The histograms of bed thickness given in figure 98 are ar ranged in geographic sequence from southwest to north east and show the general increase in thickness in that direction. Most of the carbonate rock in the Franson Member is thick bedded, the only suggestion of a re

gional variation of bedding characteristics being af forded by the fact that more of the section is very thick bedded at Hawley Creek and Big Sheep Canyon and in the Big Hole Canyon-Melrose area than elsewhere.

Carbonate rock of the Park City Formation can be divided into three major textural types: aphanitic, gran-


50

1224 1249 1301 Big Sheep Hogback Sliderock Canyon Mountain Mountain

LOCALITY

EXPLANATION

1307 Alpine Creek

Very thick bedded (greater than 1 ft)

Thin-bedded (0.02 to 0.2 ft)

Fissile (less than 0.02 ft)

FIGURE 98. Thickness of bedding of dolomite in the Grandeur Member iof the Park City Formation.

ular, and skeletal. A fourth type, which is quantita tively insignificant, consists of discrete carbonate crys tals of sand size. Both limestone and dolomite exhibit the three major textures, but a much larger proportion of the limestone is skeletal. No aphanitic or granular limestone was studied in thin section; so, the more de tailed discussion of these types will refer to dolomite only.

The asphanitic dolomite consists of an equigranular mosaic of dolomite anhedra. The average grain dia meter in most samples is between 15 and 30 microns but in some samples is as small as 5 microns and in a few is as large as 62 microns. The sorting of the dolomite grains is excellent; in a sample in which the average grain size is 20 microns, only a few grains are as large as 50 microns. Sparse euhedral rhombs of dolomite are present in most thin sections, but in only one sam ple do they total more than a few percent. The rhombs are generally either the same size as the anhedra or only slightly larger.

Detrital quartz-silt grains are rather evenly scattered through most of the dolomite. The silt constitutes gen erally less than 15 percent of the rock and in some places less than 5 percent, but a few silty dolomites con tain nearly 50 percent silt. The quartz grains are al most invariably corroded and are replaced around the perimeter by dolomite. The dolomite and detrital quartz grains in most samples of the Grandeur Mem ber are similar in size, but this generalization does not hold for grains in the Fraiison Member. Several apha nitic dolomites from the Franson Member as seen un der a binocular microscope and in thin section con tained abundant quartz sand; this evidence suggests that much of the dolomite may have originally had a

granular texture that has since been destroyed. Sev eral samples contain a few doubly terminated hexag onal prisms of authigenic quartz that are generally 0.1-0.2 mm in diameter.

Most of the dolomite examined contains about 1 per cent brown and reddish-brown iron oxide as scattered small equant grains having a maximum diameter of 15 microns, as irregular aggregates as much as 50 microns in diameter, or as streaks. Many of the smaller grains are polygonal in outline and are probably pseudomorphs after pyrite. The larger grains may originally have been aggregates of pyrite crystals.

Most of the dolomite beds described as granular in the section descriptions and on the correlation diagrams have been so identified by examination of hand speci mens with a binocular microscope. Although the na ture of the dolomite grains could not be determined, most of them seem to be skeletal fragments, probably of bryozoans; however, in the few thin sections of gran ular dolomites examined, most of the grains are not obviously organic. Bed F-40 from Canyon Camp is composed of 10 percent fine quartz sand and 90 percent dolomite; nearly two-thirds of the dolomite consists of well-sorted and rounded fine-grained pellets that are composed of an aggregate of anhedral dolomite crystals averageing less than 5 microns in diameter. The dolo mite pellets, quartz grains, and a few recognizable fossil fragments are in a clear matrix of dolomite anhedra that average about 20 microns in diameter. The sorting, rounding, size, and packing of the dolomite pellets sug gest that the pellets were transported and deposited by the same current and under the same conditions as the associated quartz sand. Several beds of the lower member of the Park City Formation at Alpine Creek consist of sandy dolomite that contains pebbles of apha nitic dolomite similar in lithology to adjacent beds. These pebbles were evidently derived intraformationally. The sandy dolomite matrix in which the pebbles are set consists of very fine quartz sand and fine-grained subangular dolomite fragments composed of extremely fine grained anhedra. Like the dolomite pebbles, the dolomite grains are probably intraformationally de rived.

The most prominent occurrences of skeletal carbonate rock are in the Franson Member of Little Sheep Creek and at Wadhams Spring. At the first locality the skele tal carbonate is mostly limestone, and at the second it is mostly dolomite; but, megascopically at least, the textures in the two sections are remarkably similar. Both the limestone and the dolomite consist mostly of medium to very coarse sand-size fragments of brachiopod and pelecypod shells and of bryozoans. Well-pre served brachiopod shells are present at several horizons


in both sections and are locally so abundant that the rock is coquinoid.

SANDSTONE

The sandstone of the Park City Formation may be divided into two groups on the basis of size and sorting of the detrital grains: (1) well-sorted very fine and fine-grained quartz sandstone and (2) somewhat less well sorted very fine grained silty quartz sandstone. The first group corresponds to the dolomitic and sili ceous orthoquartzites of Weaver and the second to his illitic orthoquartzite (Weaver, 1955, p. 186). The well- sorted sandstone group can in turn be subdivided on the basis of the presence or absence of dolomite, calcite, and chert and on the abundance of apatite and clastic chert grains; on the other hand, the silty sandstones form a rather homogeneous group. In figure 131, the grain-size distribution of a well-sorted sandstone is compared with that of two silty sandstones. As can be seen from the figure, the differences in both grain size and sorting between the two groups are small, and even the silty sandstones are rather well sorted. Neverthe less, the differences are significant and can be detected with little difficulty in hand specimens. Furthermore, the groups differ, although less sharply, in color and bedding characteristics; generally, well-sorted sand stone is thick bedded and has a high color value and little or no chroma, whereas .the silty sandstone is thin bedded and has lower color value and moderate chroma; in other words, the silty sandstone is thinner bedded, darker, and more colorful, apparently because it con tains more clay and limonite than the well-sorted sandstone.

The well-sorted sandstone ranges in modal diameter from about 0.12 to 0.2 mm. Quartz grains as large as 0.6 mm have been seen, but they are scarce. A grain- size analysis has been made for only one sample of this group (lot 1299, G-35), but visual comparison of the thin section of the analyzed sample with other thin sections of the group suggests that the sorting coeffi cient of the sample, $0=1.26 corrected for sectioning, is representative of the group as a whole. The quartz grains are mostly subangular and subroimded; the larger grains are better rounded. Well-rounded grains are scarce and are limited to the largest sizes. Most of the quartz grains are nearly equidimeiisional in thin section; less than one-fourth are noticeably elongate, and in most specimens considerably less than one-tenth are markedly so. Three-fourths to nine- tenths of the quartz grains exhibit only slight strain shadows; most of the rest are highly strained, and a very few are compound. Both potassium feldspar and plagioclase (probably oligoclase) in amounts not ex ceeding several percent have been seen in specimens

from the Grandeur Member at Alpine Creek and at Hawley Creek; most of the feldspar is unaltered. Chert grains compose not more than about 2 percent of the total clastic grains of the well-sorted sandstone of the Grandeur Member, but in the sandstone of the Franson Member, the ratio of quartz grains to chert grains is quite variable and ranges as low as 3:1. Apa tite pellets and skeletal fragments are absent in the sandstone of the Grandeur Member but are present in the sandstone of the Franson Member in amounts averaging 5 or 6 percent but reaching as much as 15 percent.

Dolomite is the most common cement, although cal cite cement is more common than one would expect from the low ratio of limestone to dolomite in the more carbonatic parts of the formation. The carbonate cement commonly composes 10-25 percent of the rock, but in many beds in the Franson Member at Big Sheep Canyon, it nearly equals the amount of the quartz sand. Texturally the dolomite cement is a mosaic of anhedra similar in size and character to the anhedra of the aphanitic dolomites. The dolomite in many samples lias irregularly replaced the periphery of the quartz grains.

Quartz overgrowths on the sand grains are common in many samples of the carbonatic sandstone, but they rarely constitute more than a few percent of the rock. A few samples contain small amounts of quartz cement, and a mosaic texture has resulted from pressure solution of the quartz grains and minor redeposition of quartz as overgrowths; the resulting rock is a compact quartz - ite having very low porosity. (See also Weaver, 1955, p. 186.) Microcrystalline quartz cements a few sand stone beds, most of which are adjacent to members of the Phosphoria Formation.

Relatively unweathered beds of the well-sorted sand stone are generally hard, very thick bedded, and of neutral hue and high color value (7 or greater). The more weathered beds are generally thin or medium bedded and soft or medium hard; they are colored shades of brown, yellowish brown, and orange (YR hues) having moderate color values (5 and 6) and moderate chromas (4 and greater). Some sandstone in the Grandeur Member at Little Sheep Creek is crossbedded.

Silty sandstone is found only in the Grandeur Member of the Park City Formation. Characterizing param eters of the size distributions of four samples of this rock type (lot 1299, G-54 and G-8; lot 1249, K-4a and K-8) are summarized in table 2. In spite of indicated differences in median diameter, three of the four samples are more poorly sorted than any analyzed sample in either the Quadrant or Shedhorn Formations. The


estimated modal grain size of all samples of the silty sandstone that were examined in thin section ranges from about 0.2 mm to the lower limits of the sand size, but all are more poorly sorted than the other Permian sandstones and the sandstone of the underlying Quad-

TABLE 2. Size parameters of sandstone from Shedhorn, Park City Quadrant, and Phosphoria Formations of southwestern Montana

Lot and sample

Size parameter

Uncorrected for sectioning

Md Md, So

Corrected for sectioning

Md Md<t> So tr<j> a<t>

Upper member of Shedhorn Sandstone and equivalents

11399 Us-183.. ...................

181. . ..... ... .171..... .............162.......... __ . . .

1234

Us-124.. ...... .117... ...............

1214

Us-74b ............. ..64c... __ .... _ .. . .57a ___ ..

To-54b _ ....

1358

Us-65b ____ ... ... 65a__._ __ . __ . __ ..

1307

Us-46..... ________ .. 44... ___ .. ____ . _

1302

Us-87... __ ... __ . __ ..

1218

RWS 103e__ __ . .. lOlc.. . ............

0.181.182.100 .092

.096

.083

.086

.125

.088

.081

.092

.092

.159

.088

.088

.130

.118

2.479 dfi

3.33 3.45

3.383.59

3.533.003.503.36

3.45 3.45

2.65 3.50

3.50

2.94 3.08

1.311.141.23 1.24

1 99

1.20

1.211.251.181.14

1.19 1.32

1.25 1.21

1.21

1.31 1.34

0.207

.107

090

------ -

.......

2 97

3 99

......

1 09

11^

1 to

0.41

o-i

.30

+0.51

-

Lower member of Shedhorn Sandstone and equivalents

1SOO

Ls-15.... ___ _. .

1214

R-29a_..__ ___ .Ls-28a_ _____________

28b ... _ ......

1302

Ls-44.... _ _____

1299

Ls-83.... ___ ..R-74_. __________

73... _. .. ..

1307

Ls-28______-.___.__________

11318

RWS 85a__.._.__

meRWS 51c _

1SB4

F-12 ___ ... __ ..........

0.106

128140

.141

.128

.103

.120

.068

.109

.138

.130

.120

3.24

9 Q7

2.849 R3

2.97

3.283.063.88

3.20

2.86

2.94

3.05

1 10

1.251 291.24

1.23

1.231.261.14

1.27

1.37

1.36

1.24

0.120

1 Kf\

164

3.05

9 7*

2 CO

2 fi1

1.14

1 90

1.241.17

O OQ

.43dsDO

0

+ f!9-.05

M

TABLE 2. Size parameters of sandstone from Shedhorn, Park City, Quadrant, and Phosphoria Formations of southwestern Mon tana Continued

Lot and sample

Size parameter

Uncorrected for sectioning

Md Mdo So

Corrected for sectioning

Md Mdo So W w

Grandeur Member of Park City Formation

1299

Q-54.. _____ - _35. 8_

1S4» 1

E Q

0.068.103.043

3.873.284.55

1.521.311.50

0.082.118.053

.114

.116

3.603.084.27

3.133.10

1.491.261.42

1.601.70

0.80.49.82

+0.060

+.17

Quadrant Formation

1218S 1133a_ .-_ . _

11346 1

W-l QQ

6a._... __ __ 9 . . . .12d_._-._

12341

0.106 3.24 1.38

0.189.112.139.129.159

.151

2.403.152.852.952.65

2.73

1.261.291.311.491.33

1.34

-

Retort Phosphatic Shale Member of Phosphoria Formation

1369

"R f 14. TiAllofc

11399

0.241.176

160

2.052.51

2.64

1.371.32

1.32

i Sieve analyses from Weaver (1955, p. 179). Sample numbers are those of Weaver.

rant Formation. Poorly defined graded laminae are common in the silty sandstone but are extremely scarce in the well-sorted variety.

The detrital grains of the silty sandstone are very similar in character to those in the well-sorted sand stone. In most samples, more than 95 percent of the detrital grains are composed of quartz; most grains are subangular, but in the coarsest fraction they are subrounded and even rounded. Chert grains compose as much as 10 percent of the detrital fraction of a very few samples, but they are not at all conspicuous in hand specimens. The quartz grains are mostly equant, and most display only slightly undulant extinction.

Weaver (1955, p. 168) reported that several of his samples contained lath-shaped quartz crystals similar to the quartz paramorphs after tridymite described by Wager and others (1953). Similar lath-shaped quartz occurs in silty sandstone from near the base of the Park City Formation at Hogback Mountains. These laths average 25 microns in diameter and 150 microns


in length and are both unicrystalline and polycrystal- line; all show inclined extinction. In one thin section similar-appearing laths radiate from a common center and seem to be fossil replacements or fillings; so, the igneous origin of the laths is by no means certain. About 1 percent of potassium feldspar and plagioclase was seen in several samples.

Dolomite makes up 40^t5 percent of many beds of the silty sandstone, and few beds contain less than 10- 15 percent dolomite. Several samples contain large equant unicrystalline anhedral dolomite grains that are similar in size to the associated quartz grains and that constitute as much as half the total dolomite, and several samples contain numerous composite grains, also similar in size to the quartz, that are composed of microcrystalline dolomite anhedra. The dolomite grains bear the same relationship to other grains and to the matrix and cement as do the detrital quartz grains: this evidence indicates that both the large unicrystalline grains and the aggregates were deposited with the quartz by currents. The remainder of the dolomite is intergranular and consists of small anhedra.

Weaver (1955, p. 186) described quartzite from the Grandeur Member at Kelley Gulch that contains 10-15 percent illite. We have not examined thin sections of these rocks from Kelley Gulch, but few similar-appear ing rocks from the same stratigraphic interval at other localities contain more than a few percent clay minerals and mica.

Weaver (1955, p. 180-185) studied the heavy miner als of five samples of silty sandstone of the Park City Formation three from Kelley Gulch and two from Sheep Creek. The most abundant nonopaque detrital heavy mineral in Weaver's samples is zircon. Tour maline is also common, and figure 136 (reproduced from Weaver's figure 11) indicates the relative abundances of the color varieties of that mineral. Weaver also observed small amounts of rutile, apatite, and garnet. Of the opaque minerals, leucoxene is by far the most common, constituting 15-30 percent of the total heavy minerals. Anatase is present as outgrowths on many leucoxene grains. Most of the heavy-mineral grains are subrounded to well rounded, and Weaver (1955, p. 180-181) concluded that most were derived from older sediments.

Most of the silty sandstone is thin bedded and hard. The sandstone is colored generally brown to yellowish orange (TR hues) having values of 5 and 6 and chromas of 4 and greater. One exception is sandstone from Dalys Spur, where the sandstone of the lower part of the Park City is hard, thick bedded, and light gray.

MUDSTONE

Mudstone occurs in both the Franson and Grandeur Members of the Park City Formation, but in the Fran son Member it is restricted for the most part to a zone in the middle of the member that is present at only two sections, those at Little Sheep Creek and Wadhams Spring. The mudstone at these two localities is thick bedded and highly dolomitic and ranges in color from pale brown where fresh to pale yellowish orange where weathered. The detrital fraction seems to consist al most exclusively of silt-size quartz.

Mudstone forms a large part of the Grandeur Mem ber of the Park City in the western part of the area. The mudstone consists of two types that differ appar ently only in color. The first type is a pale-reddish- brown (10.ff5/4) dolomitic mudstone that is mostly thin bedded and medium hard to hard; the second type is a medium-hard to hard dolomitic mudstone that ranges in color from yellowish gray to dusky yellow and in thick ness of bedding from thin to very thick. These are referred to as red mudstone and tan mudstone respec tively, in the following discussion.

Size-distribution curves of the acid-insoluble frac tions of three red mudstones and three tan mudstones from the upper part of the Grandeur at Big Sheep Canyon are shown in figure 99. The median diameter of five of the samples falls within the medium-silt class, and that of the sixth sample is in the coarse-silt class. The average median diameter of the three red mudstone samples is 5.07 phi (30 microns), which is slightly coarser than the average median diameter of 5.47 phi (23 microns) of the tan mudstone. The content of clay- size particles (finer than 8 phi) ranges from 8 to 25 percent; the average content of clay-size particles in the red mudstone is 11 percent, and that in the tan mudstone is 19 percent. The red mudstone is also somewhat better sorted than the tan mudstone, as is indicated by the sorting coefficient, tfo. The differences in size and sorting between the two groups, indicated by size curves, are not significant when tested by Student's t* but addi tional analyses might show the differences to be signifi cant. Facies changes from sandstone to mudstone within the member indicate that the median diameters range probably from at least 17 microns to 62 microns. The median size probably does not range much below 17 microns, for neither claystone nor any highly argil laceous siltstone has been seen.

The composition of the detrital fraction of the mudstone is similar to that of the silty sandstone of the Grandeur Member. The mudstone commonly contains about one percent of rather fresh-looking feldspar, a


100

DIAMETER, IN PHI

7 8

7 8

DIAMETER, IN PHI

FIGURE 99. Cumulative size distribution curves for six mudstones from the Grandeur Member of the Park City Formation at Big Sheep Canyon (lot 1224). Md<f>, phi-median diameter; So, Trask sorting coefficient.


trace of mica, and some clay, but most of the detritus consists of angular and subangular quartz silt. In thin section, mica and clay seem to constitute 15-30 percent of the rock (see also Weaver, 1955, p. 187), but the size analyses and the weak mica and kaolinite peaks on the X-ray patterns suggest that the amount of clay minerals is rather small and that much of the clay-size material is quartz. Weaver (1955, p. 174-175) showed that the clay mineral at Kelley Gulch is mostly illite, whereas that at Sheep Creek and Wadhams Spring is mostly kaolinite. X-rays of samples from Big Sheep Canyon show small amounts of muscovite or illite and possibly kaolinite. Red iron oxide evenly stains the finer grained matrix of the red mudstone.

With the exception of some highly weathered beds at Sheep Creek, all the mudstone of the Grandeur Mem ber of the Park City is dolomitic. The dolomite is pres ent in two forms. It consists most commonly of anhedra about 5 microns in diameter that occur as a rather evenly distributed intergranular matrix, but it also occurs as larger anhedra and as equant aggregates of smaller anhedra; both the larger anhedra and the aggregates are similar in size to the quartz silt and are grains rather than cement.

Thin sections show that some of the mudstone has a lamination not seen in hand specimen. The alternating laminae consist of medium- and fine-grained silt, range from 0.2 to 2 mm in thickness, and are irregular and discontinuous. Some possible microchanneling has been noted.

CHERT

Chert, both bedded and nodular, is present throughout the Park City Formation, but it is a prominent constitu ent only locally and only in the Franson Member. In outcrop, the nodular chert ranges from well-formed, round, equant bodies to lenses and extremely irregular masses. The well-formed nodules are commonly 0.4- 0.5 foot in diameter, but they range in diameter from less than an inch to a little more than a foot. Chert nodules generally constitute only a few percent of a bed, but locally they may constitute one-half or one- third. They are most common in the dolomite but are present in some sandstone and dolomitic-mudstone beds.

Weaver (1955, p. 168-171) described the nodular chert of the Grandeur Member in considerable detail, and this paragraph is based on his discussion. Microscop ically, the chert appears to be composed of tightly packed grains of quartz ranging in diameter from 1 to 60 microns and averaging 5-10 microns. The smaller grains have irregular penetrating boundaries, and all grains show undulose extinction. Bubble inclusions are abundant, and sericite and illite shreds are common. Lenses and veins of coarse-grained vein quartz and fi

brous chalcedony are present in some nodules. Electron micrographs of samples of two chert nodules are pub lished in Weaver's paper; one shows the sample to con sist of indistinct, tightly packed xenomorphic patches of quartz, and the other shows the sample to consist of distinct, tightly packed equant to prismatic, apparently polygonal particles, most of which are 1-3 microns in diameter. Weaver concludes that the grain size as measured in thin section is a "pseudo feature" and that the apparent interpenetrating boundaries and undulant extinction result from the superposition in the thin section of several individual crystals having diameters only one-tenth the thickness of the section.

Chert occurs as interbeds in dolomite in both members of the Park City Formation. Although locally a few chert interbeds may exceed 5 feet in thickness, most interbeds are less than half a foot thick. Some zones of interbedded chert and dolomite, but not individual beds, may be correlated from section to section.

Both the chert nodules and the thin chert interbeds show unequivocal evidence of replacement origin at sev eral localities. At Wadhams Spring textures in thin lenses and discontinuous beds of chert in the Franson Member closely reproduce those of bryozoan limestone; at Hawley Creek a chert bed in the lower member con sists largely of silicified corals, and at Alpine Creek a small chert nodule retains the texture of the intraformational dolomite breccia in which it occurs.

In addition to the chert nodules and the thin chert interbeds, thicker sections of bedded chert are present in the Park City Formation at several localities. The most prominent of these is at Sheep Creek, where 40 feet of bedded chert occurs near the top of the Franson Member. It consists of alternating beds 1.0-1.5 feet thick of hard yellowish-orange chert. The entire 40 feet is similar in gross lithology to beds that are else where placed in the Tosi and Eex Chert Members of the Phosphoria Formation and would also be included in one or the other of those members if its continuity with either of them could be demonstrated.

STRATIGRAPHY

GRANDEUR MEMBER

The Grandeur Member of the Park City Formation consists of the interbedded carbonate rock, carbonatic sandstone, and carbonatic siltstone that underlie the Meade Peak Phosphatic Shale Member of the Phos phoria Formation and overlie the Quadrant Formation (Cheney and others, in McKelvey and others, 1956, p. 2841). At most localities the contact between the dolo mite or the silty sandstone and mudstone of the Park City and the massive light-colored well-sorted sandstone of the Quadrant is sharp and can be located without


difficulty. Locally, however, well-sorted sandstone and dolomite are interbedded and the contact seems gradational as in parts of the Melrose area,2 at Lazyman Hill in the Gravelly Range, and at Indian Creek and Shell Canyon in the Madison Range. The -contact with the overlying Meade Peak Member of the Phosphoria is also sharp and distinct, but the Grandeur Member is distin guished with some difficulty from the similar-appearing Franson Member of the Park City in the eastern and northern parts of the areas where the Meade Peak and Rex Members of the Phosphoria Formation are not present. Although there is always some doubt in plac ing the contact in such areas, the Grandeur and Franson Members can generally be separated in the Madison Range by the character of the associated sandstone; sandstone associated with the Franson Member com monly contains conspicuous amounts of chert grains and apatite pellets and fossil fragments, whereas sand stone associated with the Grandeur Member does not. Although the division can also be made by the same criteria in several sections in the Three Forks region, the two members there must be combined in most places.

At Hawley Creek, where the westernmost section was measured, the Meade Peak Tongue of the Phosphoria is absent, and the correlation shown in plates 16 and 21 is not the only one possible; an alternative correla tion is that the Franson Member of the Park City For mation may pinch out east of Hawley Creek and, so, all the Park City at Hawley Creek may belong to the Grandeur Member. However, the correlation shown seems to be a likely one and has been followed in con structing the isopach and lithof acies maps.

The Grandeur Member has not been studied in as much detail as have the overlying strata. Fewer com plete sections of the member were measured than of the other members, and where sections were measured, the Grandeur Member was generally described in less detail than the rest of the Permian rocks. Partly for these reasons and partly because of the lack of distinctive beds or sequences of beds within the member, only the broad outline of its stratigraphy is known.

The areal variation in thickness of the Grandeur Member is shown in figure 100, and the areal variation in lithologic character, in figure 101. In general, the member thickens southwestward from a few tens of feet in the Madison Range area to a maximum of nearly 600 feet at Hawley Creek. The trend is not continuous but is interrupted by an abrupt thickening to a maxi mum of more than 380 feet in the eastern Snowcrest Range and a complementary thinning along an axis

B Pierce,- H. W., 1952, Geologic studies of the Phosphoria formation in restricted areas, faelrose Phosphate Field, Montana: Indiana Univ., Master's thesis, p. 9.

running northward from Wadhams Spring to near Dillon. The thickening in the eastern Snowcrest Range is abrupt more than 300 feet in 12 or 13 miles and perhaps as much as 280 feet in only 4 miles. Westward from the low at Wadhams Spring, the member thickens at an average rate of a little more than 12 feet per mile.

The Grandeur Member may be divided into two parts the upper terrigenous beds and the lower dolo mite. Westward along the line of sections shown in plate 16, the upper terrigenous beds are present at Hogback Mountain, where they consist of 75 feet of silty dolomitic sandstone. The average grain size of the terrigenous material is finer westward from Hog back Mountain, and at Wadhams Spring the interval consists of about 70 feet of dolomitic mudstone and dolomite. Farther west at Big Sheep Canyon most of the mudstone is red, but at Hawley Creek there is no conspicuous zone of either sandstone or mudstone, un less the beds assigned to the Franson Member are ac tually part of the Grandeur, and the part of the section that is most probably equivalent to the upper terrige nous beds consists chiefly of dolomite. East of Hog back Mountain the upper terrigenous beds have prob ably been removed by erosion that preceded deposition of the Meade Peak Phosphatic Shale Member.

The entire Grandeur Member of the Park City For mation in the Gravelly and Madison Ranges consists of the lower dolomite. West of the Ruby River the lower dolomite thickens to 310 feet at Hogback Mountain, thins to 50 feet at Wadhams Spring, and thickens again to 235 feet at Big Sheep Canyon. The lower dolomite beds west of the Ruby River are nearly all aphanitic. Chert, both as nodules and as thin beds, is more common from Wadhams Spring westward, and sandstone, of both the well-sorted and silty types, is present as sparse interbeds. Other than for the granular dolomite and dolomite-pebble breccia at Alpine Creek, the changes in thickness of the lower dolomite do not seem to be re flected in the composition or texture of the rock.

Correlation of the two units northward is uncertain, inasmuch as in the 28-mile stretch from Big Sheep Canyon to Sheep Creek, in which there is no inter mediate control, the Grandeur Member thins from 347 feet to on-ly 40 feet; most of the Grandeur Member at Sheep Creek, Dalys Spur, and in sections north and northwest of Dillon, however, correlates probably with the upper terrigenous beds (pi. 17). The Grandeur Member at Dalys Spur is composed about half of sand stone and half of dolomite; the sandstone grades south eastward into mudstone at Sheep Creek and northward into mudstone at Kelley Gulch, into dolomite and chert at Big Hole Canyon, and into dolomite at Melrose.


113° 112° ' lll c

Franson and Grandeur Members not differentiated north of lat 45°40'

MONTANA WYOMING

o

FIGURE 100. Isopach map of the Grandeur Member of the Park City Formation. Contour interval, 100 feet where member is more than 100 feet thick; 50 feet where it is less than 100 feet thick. X, control point showing measured thickness in feet; A, control point, data approximate.

In the Three Forks area, the probable equivalent of the Grandeur Member of the Park City Formation consists of aphanitic dolomite and some interbedded dolomite and chert. The dolomite may grade north ward into interbedded silty and well-sorted sandstone at North Boulder Creek. The Grandeur member in the Three Forks area can be correlated only in a gross manner with the presumed equivalent member to the south and southwest. It has not been determined whether these strata are equivalent to the entire mem ber at localities such as Hogback Mountain or to only part.

The nature of the contact between the Grandeur Mem ber and the Quadrant Formation is not well known. The greater amount of sandstone, similar in character to sandstone in the Quadrant, in the Grandeur Member at Indian Creek than in the sections at Shell Canyon and Mountain Sheep Point suggests that the Grandeur Member at Indian Creek in part interfingers with and grades into the uppermost part of the Quadrant; interfingering is also suggested by relations between the sec tions at Three Forks and at Logan (pi. 19). In neither comparison, though, is such a f acies change well docu mented, and the possibility that the Grandeur Member


113° 112° 111°

299


MONTANA WYOMING

EXPLANATION

Sand Mud Carbonate

Patterns used singly in class I areas; combined in class H and HL areas

FIGURE 101. Lithologlc character of the Grandeur Member of the Park City Formation. X, control point; A, control point, data approximate.

actually pinches out to the east cannot be rejected. To the southwest, the comparison of the Grandeur Mem ber at Alpine Creek with that at Lazyman Hill (pi. 16) also suggests that the basal part of the Grandeur Mem ber grades into sandstone to the east.

The available f aunal evidence indicates, on the other hand, that the Quadrant and Grandeur are separated by a hiatus that at least in the eastern part of the area

represents most or all of Upper Pennsylvanian time and perhaps part of Wolf campian time as well. Fusulinids of Des Moines age have been reported from about 30 feet below the top of the Quadrant at Mountain Sheep Point (Henbest, 1956, p. 59), and fusulinids reported by Henbest to be "middle or upper Wolfcamp (or pos sibly early Leonard)" in age have been found near the base of the Park City Formation at Three Forks (Wil-


liams, in McKelvey and others, 1956, p. 2857). Thus, any interfingering between the two formations must be minor and would involve only the very uppermost part of the Quadrant.

Disconformable relations between the Park City For mation and the Quadrant Formation have been reported by Theodosis 3 on the basis of thickness variations of the Quadrant and the presence of "weathered friable sand stone in the uppermost part" that was thought to mark an old erosion surface. The Park City Formation in the same area ranges from 34 to 187 feet in thickness according to measurements made by Peterson and others (1954), Theodosis, Fowler,4 and Rooney.5 Although these relations suggest disconformity in the Melrose area, they by no means prove it and may instead repre sent facies changes.

.The relation of the Grandeur Member of the Park City Formation to other formations of different lithology to the west and south is highly conjectural. Black- stone (1954) reported a limestone sequence in the south ern Lemhi Range of Idaho that contains Wolfcamp fusulinids and therefore may be a westward continua tion of the Grandeur. Farther west, the dolomite may grade into sandstone of the Wood River Formation, for Bostwick (1955, p. 944) assigned a Wolfcamp age to the upper tw^o-thirds of the Wood River near Hailey in central Idaho. The larger amount of sandstone in the Grandeur at Crooked Creek than at Little Sheep Creek (p. 17) suggests a southeasterly source of sand; this in turn suggests that at least the lower part of this lower member of the Park City Formation in south western Montana may be the equivalent of part of the sandy member of the Wells formation, much of which, according to J. Stewart Williams (1953, p. 39), may be of Permian age.

FRANSON MEMBER

The type area of the Franson Member of the Park City Formation is Franson Canyon, Utah, where Cheney (in McKelvey and others, 1956, p. 2842) applied the name to a sequence of light-gray and grayish-brown dolomite and limestone that overlies the Meade Peak Phosphatic Shale Tongue of the Phosphoria Formation and underlies the Woodside Formation. Carbonate rock of the Franson Member can be traced from the type area in Utah through western Wyoming and east ern Idaho into Montana (McKelvey and others, 1956, fig. 2). In Montana the Franson Member consists of the carbonate rock, largely dolomite, that lies between the Rex Chert Member and the Retort Phosphatic Shale

8 Theodosis, S. D., 1955, Geology of the Melrose area, Beaverhead and Silver Bow Counties, Montana : Indiana Univ., Ph. D. thesis.

4 Fowler, W. E., 1955, Geology of the Trusty Lake-Quartz Hill Gulch area, Beaverhead County, Montana: Indiana Univ., Ph. D. thesis.

6 Rooney, L. F., 1956, A stratlgraphlc study of the Permian formations of part of southwestern Montana: Indiana Univ., Ph. D. thesis.

Member of the Phosphoria Formation. It intertongues eastward with the lower member of the Shedhorn Sand stone. A western sandstone and chert facies near Dillon is included in the Franson because of the small area in which it crops out and because it does not seem to be continuous with the lowrer member of the Shedhorn Sandstone.

The contact of the Franson with the underlying and overlying units is sharp almost everywhere. Near Lima the Franson directly overlies chert of the Rex Member of the Phosphoria and directly underlies phosphorite of the Retort Member of the Phosphoria, but to the east and northeast it is separated from these two units by tongues of the Shedhorn Sandstone. In the Madison Range, where the Meade Peak Tongue of the Phosphoria is absent, the Franson Member can be distinguished from the Grandeur Member of the Park City Formation by the character of the associated sandstone, as noted in the description of the Grandeur.

The thickness and distribution of the Franson Mem ber are shown in figure 102. The greatest measured thickness of the Franson is at Wadhams Spring, where it is approximately 210 feet thick. From Wadhams Spring it thins to the north, west, and southwest. The member thins eastward and intertongues with the lower member of the Shedhorn Sandstone; at Logan and North Boulder Creek in the northern part of the area, no beds can be assigned with assurance to the Park City. At Hawley Creek the beds assigned to the Franson Member are only 40 feet thick, indicating that it may have originally pinched out a few tens of miles farther west; however, it is possible that this part of the section is actually the upper part of the Grandeur Member and that the Franson pinches out between Big Sheep Can yon and Hawley Creek.

The areal variation of the gross lithic composition of the Franson Member is shown in figure 103. The illustration shows the general uniformity of composi tion of the member, which is, of course, a reflection of the definition of the member, and clearly shows the western terrigenous facies. The dolomite of the Fran son in the Snowcrest Range is relatively low in con taminants, as is shown by the low D values on the map, but the amount of minor constituents (mostly sand and nodular chert) increases both eastward and westward. The area of cherty dolomite shown in the northern Mad ison Range may extend northward, for the Park City Formation at Three Forks contains a large proportion of chert as interbeds, lenses, and nodules.

The transition of the member from the western ter rigenous facies into the predominant dolomite facies may be followed in some detail in plate 20. At Balys Spur, the Franson contains no dolomite but consists


113° 112° 111°

301

Franson and Grandeur members not differentiated north of lat 45°40'

MONTANA V~~ WYOMING

V

CONTOUR INTERVAL 50 FEET

FIGURE 102. Isopach map of the Franson Member of the Park City Formation. X, control point showing measured thickness in feet;A, control point, data approximate.

of sandstone and subordinate chert and minor mudstone. Twenty-five miles to the south at Little Water Canyon, the upper part of the member is composed mostly of dolomite rather than sandstone, and much of the sandstone in the lower part of the member is carbonatic. Four miles farther south at Big Sheep Can yon, the upper half of the Franson is composed mostly of carbonate rock, cherty carbonate rock, and bedded chert, and the lower half is composed of interbedded granu lar carbonate rock, sandy carbonate rock, and dolomitic sandstone; several thin tan dolomitic mudstone beds are present in the middle of the member. Nine miles far ther southeast, at Little Sheep Creek, the Franson is composed mostly of carbonate rock, half of which is

709-931 O 63 3

granular or skeletal, but about a quarter of the mem ber is composed of tan dolomitic mudstone that occurs in the middle of the section. Thus, as one traces the member southward, carbonate rock makes up a pro gressively greater proportion of the section, the sand stone is progressively more carbonatic, and mudstone forms a progressively greater proportion of the terri genous material. The change in gross aspect of the member from Dalys Spur to Little Water Canyon, a distance of 25 miles, seems no greater than the change from Little Water to Big Sheep Canyons, a distance of only 4 miles, or from Big Sheep Canyon to Little Sheep Creek, a distance of only 9 miles. One minor difference in the facies distribution, shown in plate 20, is that glau-


113° 112°


MONTANA WYOMING

EXPLANATION

Sand Chert CarbonatePatterns used singly in class I areas; combined in

c/ass I and 1R'areas

Isopleth of D valuesContour interval 25 units

-25 -

Isopleth of ratio

calcitetotal carbonate X'100

FIGURE 103. Lithologic character of the Franson Member of the Park City Formation. X, control point (numeral is value of D function).

conite occurs in the sandy carbonate-carbonatic sand stone sections but not in the sandstone section at Dalys Spur or the limestone section at Little Sheep Creek.

A similar change in facies from sandstone to dolo mite takes place north of Dalys Spur (pi. 20) and

northeast of Kelley Gulch (pi. 19), but the nature of the change is not shown by the sequence of sections as well as it is in the sections south of Dalys Spur. The sandstone does not grade into mudstone northward and northeastward, but it either grades directly into dolo-


mite or else from sand to bedded chert and thence to dolomite.

From the mixed sand and carbonate section at Big Sheep Canyon, the sandy beds in the upper and lower parts of the Franson member grade eastward into dolo mite at Wadhams Spring, whereas the sandy beds in the center part grade into dolomitic mudstone (fig. 12). The mudstone zone may be represented by silty dolo mite at Sawtooth and Hogback Mountains, but no trace of it is found at Sliderock Mountain or in the sections east of the Ruby River. Nearly half of the carbonate rock is granular or bioclastic in all sections from Big Sheep Canyon to Sawtooth Mountain, but from Hog back Mountain east it is nearly all aphanitic, even though the dolomite is sandy in the Gravelly and Madison Ranges. In the western section, the granular dolomite does not seem to be restricted to any part of the member but occurs throughout the section. Per haps the only generalization that can be made is that at most localities the basal carbonate of the member is aphanitic.

Two zones of thin chert layers, lenses, and nodules are the only beds within the Franson Member that can be traced widely. The two zones are most conspicuous at Wadhams Spring (p. 21), where the upper consists of nodules near the top of the dolomitic mudstone and the lower consists of discontinuous beds, lenses, and nodules near the base of the dolomitic mudstone. The lower cherts in particular preserve the textures of skele tal carbonate rock. The westward correlatives of the upper zone are not known with any certainty, but the lower zone can be traced with confidence to the sections in the Tendoy Mountains west of Lima. The two chert zones converge to the northeast. They are distinguish able as separate zones at Sawtooth Mountain, but at Hogback Mountain they form a single zone of nodules and interbeds. The chert zones cross major lithologic boundaries and pass eastward from the sandstone-car bonate rock facies into dolomitic mudstone and finally into dolomite.

Neither the upper nor the lower contact of the Fran son Member can be considered a time plane. Evidence that the lower contact crosses time horizons may be seen in plate 20, where in the sections from Little Water Canyon to Sheep Creek, the contact between the Rex Chert and Franson Members crosses a phosphatic bed. If the phosphatic bed was deposited nearly synchron ously over the area, as is suggested by its uniqueness in this part of the section, the contact between the Fran son and Rex is older at Dalys Spur than it is1 either at Sheep Creek or near Lima.

The upper contact of the Franson may nearly coincide with a time plane in the western part of the area, where

the member is directly overlain by the Retort Phos phatic Shale Member of the Phosphoria Formation; but to the east, where a tongue of the Shedhorn Sandstone, is equivalent to the upper part of the Franson of the Lima area, the upper contact of the Franson is older than it is in the Lima area.

As with the Grandeur Member, the exact manner in which the Franson Member terminates to the east is not clear. Certainly the interval is in part represented by sandstone of the lower member of the Shedhorn, and the dolomite itself undoubtedly thins eastward. In dividual beds probably pinch out eastward and hiatuses there are probably more numerous and of greater time significance.

PHOSPHORIA FORMATION

GENERAL CHARACTER AN1> DISTRIBUTION

The type locality of the Phosphoria Formation is Phosphoria Gulch, Bear Lake County, Idaho, where the formation was named by Richards and Mansfield in 1912 (p. 684). Two members were recognized: the phosphatic shale member, about 200 feet thick, and the overlying Rex Chert Member, consisting of 150 feet of bedded chert overlain by 100 feet of mudstone and cherty mudstone.

In 1956 (McKelvey and others, 1956, p. 2844-2850), applied the name Meade Peak Phosphatic Shale member to the phosphatic shale of the type section, restricted the term Rex Chert Member to the 150 feet of bedded chert, and applied the name cherty shale member to the upper mudstone. The member names Meade Peak and Rex were extended to beds in western Wyoming and from there to beds in southwestern Montana on the basis of work by Sheldon (McKelvey and others, 1953).

Three members of the Phosphoria Formation are not found at the type locality of the formation; these are the Retort Phosphatic Shale Member, named in Mon tana and extending southward to western Wyoming (Swanson in McKelvey and others, 1956, p. 2850), the Tosi Chert Member, named in western Wyoming and extending into Montana (Sheldon, in McKelvey and others, 1956, p. 2841), and the lower chert member, present only in western Wyoming (Sheldon, in Mc Kelvey and others, 1956, p. 2845).

In most of southwestern Montana, four of the six members of the Phosphoria Formation are present. These are, in ascending order, the Meade Peak Phos phatic Shale, the Rex Chert, the Retort Phosphatic Shale, and the Tosi Chert Members. In addition, beds betweeen the Retort and Tosi Members at Big Sheep Canyon are tentatively assigned to the cherty mudstone member. The Rex chert and Meade Peak Phosphatic Shale Members pinch out east of the Gravelly Range


113° 112° 111°

EXPLANATION

-IOO-

IsopachContour interval 50 feet

30

Isopleth of percent of the formation composed of the phosphatic shale members

Contoured at 10, 30, and 50 percent

FIGURE 104. Isopach map of the Phosphoria Formation. X, control point showing measured thickness in feet:approximate.

k, control point, data

and north of Big Hole Canyon, but where present they are separated from the Retort Phosphatic Shale Mem ber by the Franson Tongue of the Park City Formation.

The thickness and distribution of the Phosphoria Formation are shown in figure 104. The location of the featheredge of the formation northeast of Three Forks

is based on work by Klemme." McMannis (1955, p. 1404) described 0-26 feet of chert breccia in a sandstone matrix that crops out along the east flank of the Bridger Range north and northeast of Bozeman. McMannis

6 Klemme, H. D., 1949, The geology of Sixteen Mile Creek area, Mon tana : Princeton Univ., Ph. D. thesis.


questionably assigned the unit to the Jurassic, but the similarity of these beds to the conglomerate of Permian age described by Klemme suggests that the conglomerate of the Bridger Range may also be Permian.

Near the mouth of Rocky Creek Canyon, southeast of Bozeman, the following sequence is exposed on top of typical Quadrant Formation: 5 feet of conglomeratic sandstone grading up into cherty carbonate rock and calcareous shale; 11 feet of nodular- to medium-bedded chert and limestone and shale interbeds; 6 feet of mas sive sandy carbonate rock; 3 feet of fine-grained cal careous sandstone containing angular chert fragments at the top; 3 feet'of fine-grained thick-bedded carbonate rock; 5 feet of chert; 2 feet covered; and 1 foot of fine grained white sandstone. The overlying interval is covered for a distance from its base to the Jurassic beds overlying it. The strata described above resemble units of the Permian interval to the west, in that they con tain phosphate pellets and spicular chert. Cobban, Imlay, and Reeside (1945) redescribed the type section of the Ellis Formation (Jurassic) at this locality as including, on top of the Quadrant Quartzite, 5 feet of conglomerate, 3 feet of limestone, and 84 feet of interbedded gray shale, calcareous shale, and limestone, the lowermost 23 feet of which is shale. It is difficult to reconcile the two sections overlying the Quadrant unless it is assumed that the rocks called Quadrant by them are part of the quartzite at the top of the section. No fos sils were found in the section, which was measured near the highway and in less detail than most other sections described in this report. However, specimens were collected of each bed measured, and in thin sections of these, the sponge spicules, phosphate pellets, and spicule canal fillings typical of the Phosphoria were noted, particularly in samples from the top bed of the sequence.

The Phosphoria thickens south westward from Boze man, and the maximum thickness of 330 feet occurs at Big Sheep Canyon.

The Rex and Tosi Chert Members constitute most of the Phosphoria, and in only a few places do the two phosphatic shale members constitute more than half of the formation.

L.ITHOL.OGY

FREQUENCY OF ROCK TYPES

Rocks of the Phosphoria Formation consist of mix tures of five major constituents: (1) authigenic microcrystalline quartz in the form of chert; (2) carbonate fluorapatite in the form of isotropic or microcrystalline pellets, oolites, and skeletal fragments; (3) calcite and dolomite; (4) clay minerals and detrital quartz; and (5) carbonaceous matter. All the constituents except carbonaceous matter occur in sufficient amounts to

form the major part of many beds. Most rocks of the two chert members are rather simple mixtures of authi genic microcrystalline quartz and minor clay and detri tal quartz, but combinations of three or more of the major constituents are common within the two phos phatic shale members. This lithologic character is best seen in rocks of the Retort Phosphatic Shale Member, for which more data are available than for other members.

Figure 105, illustrating the gross mineral composi tion of the Retort Phosphatic Shale Member, was con structed from analyses of rocks at eight localities. The number of samples at each locality is roughly propor tional to the thickness of the member at that point, and the localities are relatively evenly spaced over the area; so the diagram is probably representative of the member as a whole in southwestern Montana. In plotting the samples the amount of carbonaceous matter was sub tracted and the amount of the remainder of the constit uents recalculated to 100 percent. The points were plotted on the triangular diagram and then contoured in a manner similar to that used in contouring petro- f abric diagrams.

Perhaps the most striking feature shown by figure 105 is the near absence of mixtures of significant amounts of the carbonates with either the detrital sili cates or apatite. On the other hand, apatite is mixed in nearly all proportions with the quartz and clay end member. Even so, two conspicuous modes in the apa tite-silicate mixtures are apparent; the two most com mon rock types are (1) mudstone and (2) highly phosphatic mudstone and argillaceous phosphorite. The barren zone between the quartz and clay-apatite join, and the band representing the silicate-apatite mix tures results from the presence in most of these rocks of gypsum, iron oxides, pyrite, and soluble silicates.

OCCURRENCE OF CARBONACEOUS MATTER IN THE RETORT PHOSPHATE SHALE MEMBER

Carbonaceous matter is a universal and characteristic component of the shale members, although it is nowhere a dominant constituent. The relations of carbonaceous content to the other constituents of the Retort member are shown in figure 106. The carbonaceous content for each sample was noted at the proper position in the tri angle, a 1-percent-area triangle was moved systemati cally over the area of the larger triangle, and the aver age of all values within the 1-percent area was noted at each stop. The resulting average values were then contoured.

There are two bands of high carbonaceous rocks. The most conspicuous coincides approximately with the highly phosphatic mudstone mode shown in figure 106; the second very roughly coincides with the mudstone


EXPLANATION APATITE

Sample density, in percent

QUARTZ CLAY Feldspar Mica

CALCITEDOLOMITEGypsumPyriteLimoniteSoluble silicates

FIGURE 105. Mineral composition of rocks in the Eetort Phosphatic Shale Member of the Phosphoria Formation. Analyses of 97 samples representing every third bed at localities 1224. 1234, 1249, 1253, 1299, 1319, 1362, and 1363 were plotted on the compositional triangle and contoured by use of a triangle having an area 1 percent that of the compositional triangle. Major constituents in upper-case letters; minor constituents in lower-case letters.

mode. Both the high-grade phosphorites and the car bonate rocks contain little carbonaceous matter.

Figure 106 shows only average values; therefore, a frequency diagram of the organic content of the same samples is shown in figure 107. More than half the samples contain less than 4 percent carbonaceous mat ter and more than 90 percent of the samples contain less than 10 percent. The highest value reported is 23 per cent for bed Rt-193 at Big Sheep Canyon, which con tains 5.7 percent P2O5 and 36.7 percent acid insoluble material.

The relation of carbonaceous matter to other constit uents can be studied in more detail in the Retort Mem ber at Sheep Creek (lot 1234), where 16 of the samples that have been analyzed for acid insoluble, A12O3, and Fe2O3 have also been analyzed for carbonaceous matter.

Fe O

A1203

1 0. 789

r.,o,

2 0. 5262. 733

Carbonace ous matter

0.3542. 5252. 615

The correlation coefficients between constituents in these samples are listed in the following table:

1 Coefficient significant at the 1-percent level.2 C oefficient significant at the 5-percent level.

The correlation of carbonaceous matter with acid insoluble is not significant, but the correlation of car bonaceous matter with A12O3 is significant and probably reflects the commonly observed tendency of carbona ceous matter to be concentrated in finer grained sediments (Trask, 1939, p. 433). The correlation of


APATITE EXPLANATION

Carbonaceous content, in percent

307

10-20

QUARTZ CLAY Feldspar Mica

CALCITEDOLOMITEGypsumPyriteLimoniteSoluble silicates

FIGURE 106. Relation of content of carbonaceous matter to rock composition in the Retort Phosphatic Shale Member of the PhosphoriaFormation. Based on the same samples as used in figure 105.

carbonaceous matter with. Fe2O3 is also statistically sig nificant and probably reflects a direct relation between carbonaceous matter and reducing conditions in the original sediment.

PHOSPHORITE

Phosphorites are rocks in which apatite is the domi nant constituent.

There is little uniformity in color among the phos phorites as seen in outcrop or in trenches. Perhaps the only generalization that can be made is that the phos phorites are nearly all low in chroma. The frequency distribution of value (the measure of darkness) for phosphorites of the Retort Member is shown for several localities in figure 108. The lack of any regional trend in the value suggests that the differences in color as seen

at the surface may in large part be a function of the degree of weathering. The frequency distribution of the value for hard phosphorite is compared with that for medium and soft phosphorite in figure 109; this particular comparison is made because the harder beds are assumed to be generally less weathered. The differ ences between the two distributions were tested by x2 and were found to be highly significant (P<1 per cent) ; therefore, the medium and soft phosphorites are lighter in color. The most highly weathered section is at Wadhams Spring, where the rocks were weathered deeply prior to deposition of a Tertiary conglomerate. Here 75 percent of the phosphorites have color values of 7 or more.

In relatively fresh surface exposures, oolitic and skeletal phosphorites are commonly lighter in color


50-|

H 4(HzUlO trUJQ- 30H

OZ 20-

OUJtr 10-

0 2 4 6 8 10 12 14 16 18 20 22 24

CARBONACEOUS MATTER, IN PERCENT

FIGURE 107. Frequency distribution of carbonaceous matter in the Retort Phosphatic Shale Member of the Phosphoria Formation. Based on the same samples as used in figure 105.

than pelletal phosphorite, partly because the oolitic and skeletal beds originally contained less carbonaceous matter than the pelletal phosphorites and partly be cause many of the skeletal and oolitic beds are more pervious and weather more rapidly. Inasmuch as the Meade Peak Member contains generally more oolitic and skeletal phosphorite than the Retort Member, it is

distinctly lighter in color than the Retort over much of the area.

The phosphorites are somewhat more uniform in thickness of bedding than in color. About 50 percent are thin bedded, and about 40 percent are thick bedded; the rest are equally divided between fissile and very thick bedded types.

The phosphate-bearing mineral in the Phosphoria, as in most marine phosphorites, is carbonate-fluorapatite (Altschuler and Cisney, 1952). The apatite crystals in many grains are either obscured by inclusions or are too small to be resolved, but anisotropism is much more common than one would expect from descriptions in the literature. Many of the grains are composed of minute weakly biref ringent crystals having an apparent crystal size of 1 or 2 microns; the resulting pin-point extinction closely resembles that of chert. This type is termed "microcrystalline apatite" in this report. An- isotropic apatite also occurs as concentric laminae with in or as exterior rings about apatite grains. Individual crystals cannot be distinguished, but their mass orienta tion with the C axes arranged radially (the slow ray vibrates tangentially) results in weakly biref ringent, somewhat fibrous-appearing rings that exhibit the spherulitic cross. This type is termed "microfibrous apatite.'"1 Most skeletal fragments also show a weak, streaky birefringence that probably also results from

H 60f-Z

40

20

Cedar Creek 1256

Dalys Spur 1222

EXPLANATION

Value

Melrose area 1359, 1366

7-9 (Very light)

5 and 6 (Light)

60

40

20

3 and 4 (Dark)

Big Sheep Canyon 1224

Blacktail Creek 1302

Hogback Mountain 1299

Gravelly Range 1300,1307

Madison Range 1214,1362

1 and 2 (Very dark)

FIGURE 108. Frequency distribution of value (darkness) for phosphorite of the Retort Phosphatic SLale Member of the Phosphoria Formation.


o2] 60

- 40

O

=> 20 O

58 samples 64 samples

J

| |

Wadhams Sprinf

EXPLANATION Value

D7-9

(Very light)

5 and 6 (Light)

3 and 4 I (Dark)

^^u1 and 2

(Very dark)

Hard phosphorite Medium-hard and soft phosphorite

Data from following lots: 1222, 1224, 1234, 1247, 1256, 1257, 1299, 1302

FIGURE 109. Effect of weathering on value (darkness) of phosphorite.

mass orientation of minute crystals. In general, the anisotropic grains occur in the lighter colored rocks. Yet, patches of anisotropic material have been observed in some of the darkest colored phosphorite, and many very light colored apatite grains, particularly in phos phatic sandstone, are isotropic.

Crystallite sizes have not been determined by means of X-ray techniques for any of the Phosphoria apatite, but Arrhenius and others (1957) report marine in organic apatite having crystallite sizes greater than 20,000 angstroms (2 microns).

The apatite grains consist of three major morphologic types: pellets, skeletal fragments, and oolites. Pellets are grains having no regular internal structure. Most pellets are of fine- and medium-sand size, although some may be as large as 1 or 2 mm in diameter; few are of silt size. Many pellets are elongate in section; the long diameter is as much as 3 times as long as the short di ameter, but most pellets are equant or only slightly ellip tical in section. The pellets may be well formed and regular in shape and have distinct borders or may be somewhat irregular in form and have indistinct borders. The color as seen in thin section ranges from moderate brown (YR 4/4) in the more argillaceous rocks to light brown (10T7? 5/6) or lighter in the less argillaceous rocks. Most pellets contain numerous very fine quartz- silt particles and mica shreds that are randomly ori ented, and most are clouded by carbonaceous matter. Some pellets, mostly dark-colored ones, contain foraminiferal tests as nuclei (fig. 110), and a few contain silt inclusions arranged in loops and swirls that may be tests of arenaceous Foraminifera. Although most pel lets are structureless, some contain several indefinite, poorly defined round areas f ormed by finer crystal size or by darker color. The several round areas within a pellet are about the same size and are closely packed, having tangential contacts.

The term ''oolite" is restricted to apatite grains hav ing a conspicuous concentric structure. The structure may be defined by color rings or by rings of apatite of

FIGURE 110. Photomicrograph of cherty phosphorite containing abundant foramlniferal tests that form the nuclei of pellets (bed Rt-8, lot 1215, Madison Range). Pellets are generally oval to elliptical and have smooth outer rims that are free of silty inclu sions. Some are shattered. Chert fills interstices between pellets, cracks in pellets, and cells of fossils. Oolitic rings have formed around the exterior of some pellets.

different crystal habit, which is the more common type. The rings consist of either alternating microfibrous and microcrystalline apatite or alternating microfibrous and apparently isotropic apatite, but in both types the microfibrous rings are the thinner. Most of the oolites have formed about nuclei of quartz or chert grains, skeletal fragments, or, commonly, apatite pellets. Complete gradation can be found from pellets surrounded by a single ring of microfibrous apatite to oolites containing no observable pellet nucleus. Several pellets may be surrounded by a sheath of rings, or several oolites may together form the nucleus of a compound oolite. In contrast, oolites in a few beds are surrounded by a thick ring of microcrystalline or aphanitic apatite similar to that forming pellets. Most oolites are of medium-sand size, and the extremes of silt size and very coarse sand size are uncommon. The oolites are generally some what elliptical in section, and nearly all are well rounded.

The phosphatic skeletal fragments consist of bones, scales, teeth, and linguloid-brachiopod shell fragments, which were all originally highly phosphatic; however, only a few fragments can be classified as one or the other of the skeletal types. Fish teeth and bones and cosmoid fish scales have been identified, but many frag ments consist of either dense enamellike material or spongy bonelike material that is probably skeletal but


that cannot be more closely identified. A few frag ments are composed of alternate layers of closely spaced diagonal striations and are probably linguloid shell fragments. All types of skeletal fragments may be seen in a single specimen, but scale, bone, and teeth fragments seem to be more common than shell frag ments. Most skeletal fragments are light colored and lath shaped in thin section but show great variety in both size and shape. The fragments may be angular, or, as in sandy rocks, well rounded.

Nodules constitute a fourth type of grain that is con spicuous where present but is quantitatively unim portant in southwestern Montana. Most nodules occur in pelletal beds, where they constitute a minor part of the total apatite. They are composed of pellets cemented by apatite, which are identical to those in the matrix, and have resulted probably from local cementation in place. The nodules range generally from 15 to 30 mm in diameter. Nodules that occur in sandy and oolitic phosphorite beds are probably of clastic origin.

Pellets are by far the most common type of apatite grain and are present in all phosphorites examined. They may constitute all the apatite or may be mixed with skeletal fragments, oolites, or both. These rela tions are illustrated in figure 111, which is based on estimates of amounts of the types seen in thin sections. The pelletal end member is the only modal occurrence.

The phosphorites may be divided into two broad types: (1) those that were sorted and winnowed by currents and (2) those that were not, The phosphorites that show evidence of sorting and winnowing may con sist entirely of pellets or of mixtures of pellets, oolites (fig. 110), and skeletal fragments (fig. 112,4). They are characterized by well-formed grains having distinct

Skeletal fragments

Pellets Oolites

FIGURE 111. Relative abundance of the three principal types of apatite grains in thin sections of phosphorite from the Phosphoria Formation. Each small circle represents one sample.

boundaries and by the absence of a fine-grained detrital matrix. The apatite grains are mostly light colored in thin section; grain contacts are mostly tangential, and elongate grains are imperfectly oriented subparallel to the bedding. Quartz-sand grains are common, both as oolite nuclei and as separate grains. The rock may be cemented by clear microcrystalline apatite, by microcrystalline quartz (fig. 1125), or by poikiloblastic calcite. The evidences of strong current action are as fol lows : (1) Many of the rocks contain a variety of apatite grain types that had different histories; (2) many pel lets contain fine-grained quartz-silt and mica inclusions similar to those found in muddy phosphorites, whereas the only matrix material present is quartz sand, which suggests that the grains formed in a more tranquil en vironment than that in which they finally accumulated; (3) the imperfect orientation of elongate grains sug gests deposition of the grains by currents, as orienta tion produced by post-depositional processes such as compaction would be more uniform; and (4) the tangential contacts between apatite grains indicate that the grains were deposited as solid particles and that they did not form in place.

The phosphorites that do not show evidence of ap preciable sorting and winnowing by currents are dark, pelletal, and commonly argillaceous. The pellets them selves are dark brown in thin sections and contain many quartz-silt grains and mica shreds as inclusions. Where the pellets are in contact with each other, the boundaries are distinct and are commonly mutually accommodat ing, but where surrounded by silt and clay, the pellets are generally poorly formed and have indistinct bound aries. Many muddy phosphorites consist of laminae, 0.1 to about 2 mm thick, of phosphorite and muddy phosphorite or phosphatic mudstone. Within the muddy layers the pellets may be isolated in the argillace ous matrix or they may be concentrated in small clusters and lenses. Markedly elongate pellets are well oriented parallel to the bedding (fig. 112*7). The features that suggest the absence of strong currents are as follows: (1) Inclusions within pellets are similar in size and character to the matrix material, suggesting that the pellets formed in a muddy environment; (2) the fine grained silt and clay matrix would have been removed by any current strong enough to transport the apatite pellets; and (3) the presence of carbonaceous matter indicates a lack of oxygenated (and thus strongly agi tated) water.

Although the evidence indicates that the pellets were not transported but were formed at the site of accumula tion, no evidence has been found to determine whether the pellets formed at the surface of the sediment or within the sediment during diagenesis.


FIGURE 112. iPhotomicrograplis of phosphorites. A, Phosphorite containing quartz-sand grains (g) and apatite oolites (o), pellets (p), and skeletal fragments (s). Note oolite nuclei consisting of quartz-sand grains (gn) and apatite pellets (pi). Ordinary light. B, Pelletal, oolitic phosphorite cemented by microcrystalline quartz. Most oolites contain a pellet nucleus. Ordinary light. C, Pelletal argillaceous phosphorite showing poorly defined laminae, silt and clay matrix, and elongate, poorly defined pellets. Ordinary light. \D, Pelletal phos phorite showing mosaic tecture.


Figure 113 is the size-distribution curve of a phospho rite having several of the features that indicate that the pellets were not transported; yet, the pellets are well sorted, and the distribution is log normal, except for finer sizes. Thus, in spite of evidence in thin sections that the pellets were not transported, the size distribu tion differs little from that of a well-sorted sandstone.

Some pelletal phosphorites cannot be classed in either group. Grain borders are distinct, grain contacts are tangential, elongate grains are imperfectly oriented, and inclusions in the pellets are much smaller than the grains of the detrital matrix. The pellets, however, are all of one type, and the matrix grains, although much larger than inclusions in the pellets, are too small to be hydrau lic equivalents of the pellets. These phosphorites may originally have contained much clay and silt that was winnowed by currents not strong enough to transport the pellets any significant distance.

A few relatively pure phosphorites consist of mode rate-brown pellets that are tightly packed and have a mosaic texture (fig. 112Z>). Silt and clay inclusions,

100

80

Q- 60

40

20

M/<6=2.64

So = 1.32

are present but are less abundant than in more argil laceous phophorites. The mosaic texture suggests that pellets were soft at the time of deposition and thus could not be transported. Presumably the current was sufficient to prevent silt from being deposited but was insufficient to move the pellets.

Many features of the phosphorites described in the foregoing discussion are similar to those described by Lowell (1952) in his excellent study of the phosphatic rocks near the type area of the Phosphoria Formation in southeastern Idaho. Lowell (1952, p. 38-39) also found evidence that some beds have been reworked by currents or waves, whereas other beds have not. Al though his terminology differs from that used herein, his descriptions of the phosphorites could be substituted in this report with little change.

The similarities of the textures of the Phosphoria phosphorites to those of the Bahaman calcareous sands described by Illing (1954) are striking. Pelletal phos phorites of the Phosphoria are similar to Bahaman cal careous sands; phosphatic nodules, to calcareous grape-

98

95

90

85

80

70

60

50

40

30

20

15

10

7

1 2 3 4 5123. 45

DIAMETER, IN PHI

FIGURE 113. Size distribution of pellets in a muddy pelletal phosphorite. Thin-section size analysis of bed Rt-96, lot 1299 ; not corrected forsectioning. Curve on right plotted on logarithmic probability paper.


stone aggregates; and phosphatic oolites, to calcareous oolites. The photographs in Tiling's paper could well illustrate Phosphoria phosphorites except for differ ences in composition. There are, of course, some differ ences in texture the calcareous silt of the Bahamas has no phosphatic counterpart in southwestern Montana, and the detrital quartz and silicates of the Phosphoria do not exist in the Bahamas. Nevertheless, the very great similarities in texture must indicate corresponding similarities in the mode of origin.

MTTDSTONE

The mudstone and the phosphatic-mudstone modes shown in figure 105 are so distinct that one might expect accompanying differences in texture and structure, but for the most part, these differences do not seem to exist. Frequency distributions of thickness of bedding, hue, chroma, and vane have been compared for the two types of mudstone, but the x2 test indicates that the differences are not significant. A more subtle difference, however, can be shown to exist in at least one locality. In the Ketort Member at Sheep Creek, the acid insoluble/A!2O3 ratio averages 5.27 for phosphatic mudstone but aver ages 6.32 for weakly phosphatic mudstone. The differ ence is highly significant (P<1 percent), according to Student's t test that is, the detrital fraction of the weakly phosphatic mudstone contains a significantly smaller proportion of A12O3 , and thus of clay, than does the detrital fraction of phosphatic mudstone. It should be emphasized again that the assumption that the acid- insoluble content is the detrital fraction is only approx imately correct inasmuch as at least several percent of the silicates in mudstone may dissolve in the procedure used.

Most of the mudstone of the Phosphoria is thin bedded; but about 20 percent of the mudstone in the measured units is fissile, and less than 5 percent is very thick bedded. The thin-bedded mudstone is darker in color than the thick-bedded mudstone (fig. 114); this relation is possibly explained by Ingram's observation (1953, p. 877) that carbonaceous matter increases the tendency toward parallel arrangement of the clay par ticles. Ingram (1953, p. 871) also stated that in the suite of rocks he examined the mudstones having a flaggy structure (splits into fragments with two flat parallel sides and with the width and length much greater than the thickness) are predominantly black or dark gray, whereas those having a flaky structure (splits into uneven flakes, thin chips, and wedgelike fragments) are predominantly gray or gray black. In the Phosphoria, however, the opposite relation exists. The best example is at Big Sheep Canyon, where the black and olive-black highly carbonaceous mudstone of

the Retort is flaky, whereas the olive-gray carbon-poor mudstone of the cherty shale member is platy.

About one-third of the mudstone beds of the Phos phoria are neutral in hue; most of the rest have YR hues and low chromas. The value is variable over the region but may be rather consistent in any one exposure (fig. 114). The variability in value seems to be re lated more to conditions of exposure rather than to any regional trend and contrasts with the strong regional trend in the content of carbonaceous matter. To test the effect of weathering on color, the frequency distri butions of hue, chroma, and value of soft mudstone were compared with those of hard mudstone by means of the X 2 test. Differences in hue and chroma are not sig nificant, but differences in value are highly so, as the soft mudstone is lighter in color (fig. 114). No sig nificant differences in the thickness of bedding were found between hard and soft mudstone. Relatively unweathered mudstone is thus generally hard, thin bedded, and dark gray and brownish gray to black and brownish black. Weathering lightens the color and re duces the hardness but does not greatly affect the chroma or thickness of bedding.

The mudstone consists of mixtures of quartz silt, clay, apatite, and carbonaceous matter. The quartz silt is angular and contains a large proportion of elongate grains, but it is otherwise similar to the detrital quartz in sandstone of the Park City and Shedhorn Forma tions. Small amounts of both plagioclase and potas sium feldspar have been noted in X-ray patterns of some, but not all, of the mudstone, but they have not been observed in thin section.

Clay minerals have been identified from X-ray pat terns of bulk samples from several beds at Big Sheep Canyon, Sheep Creek, Hogback Mountain, and the Centennial Mountains. Illite and kaolinite are pres ent in nearly all the samples, but illite is dominant; montmorillonite has been detected. Herr 7 studied the fraction containing particles less than 2 microns in size of several samples from Big Sheep Canyon and concluded that the dominant clay mineral is a mixed- layer illite-montmorillonite. Rooney,8 also working with fine-grained separates, found that illite is the most abundant clay mineral in the sections near Three Forks and that kaolinite, chlorite, and mixed-layer illite- montmorillonite are minor accessories. In the Melrose area, however, Rooney found that montmorillonite is very abundant and in places dominant, and that kao linite is common. He believed that the montmorillo-

7 Herr, G. A., 1955, Clay minerals in the Phosphoria formation in Beaverhead County, Montana : Indiana Univ., M.A. thesis.

8 Rooney, L. F., 1956, A stratigraphic study of the Permian forma tions of part of southwestern Montana: Indiana Univ., Ph. D. thesis, p. 54-61.


Soft mudstone (80 beds)

Hard mudstone (84 beds)

Thin-bedded mudstone (131 beds)

Thick-bedded mudstone (49 beds)

80n

Big Sheep Canyon Dalys Spur Cave Creek

EXPLANATION

Value

Hogback Mountain

1 and 2 3 and 4 5 and 6 7 and over

FIGUEH 114. Value (darkness) of mudstone of the Retort Phosphatic Shale Member of the PhosphoriaFormation.

nite and kaolinite of the Melrose area most probably re sulted from hydrothermal alteration.

Apatite pellets in the mudstone are dark colored, com monly elongate, of fine- and medium-sand size, and dif fer only in abundance from those in dark argillaceous phosphorite. Sparse bone, scale, or tooth fragments are present in many samples.

Carbonaceous matter is seen in thin section as black and brown pigment that is generally concentrated in the more argillaceous parts of the specimen. The car bonaceous matter in some samples is so abundant that the thin sections are opaque. Rooney (1956) found the C 13/C12 ratio of organic carbon in the Phosphoria of Montana to range from 89.80 to 91.25, values similar to those of modern stagnant water plants as determ ined by Wickman (1952, p. 252). According to Craig

(1953) these values are also typical of the organic car bon of both petroleum and marine shales.

Iron oxide is ubiquitous in the mudstone and stains the argillaceous material yellow and brown. Pseudo- morphs of iron oxide after pyrite are scattered through most thin sections as minute grains; in other samples aggregates of the pseudomorphs form clusters and streaks. The Fe2O3 content rarely exceeds 5 percent and averages about 2 or 3 percent. (See analyses for Sheep Creek, lot 1234.)

The relative proportion of the various constituents composing the matrix are difficult to determine in thin section because of the extremely small grain size; the size distribution was not determined by sedimentation techniques because of the difficulty in dispersing the grains in rocks saturated with carbonaceous matter.


However, estimates of the relative amounts of quartz and clay in the mudstone can be made by means of the ALO3 analyses. If all the A12O3 of the mudstone in the Retort Member at Sheep Creek is in illite (an as sumption at least partially justified by X-ray data) hav ing an A12 O,, content of 26 percent (Grim, 1953, p. 372), then the acid insoluble/ALO., ratios indicate that about 75 percent of the detrital fraction of the phosphatic mudstone and 60 percent of the detrital fraction of the weakly phosphatic mudstone are clay. Inasmuch as some of the detrital silicates are soluble, these percent ages are a little too large, but the A12O3 content assumed for illite is probably near the maximum. If the illite is similar in composition to those analyzed by Kerr and others (1950) and contains only about 18 percent A12O3 , then all the detrital fraction of the phosphatic mudstone is clay. Whatever the composition of the illite, much of the mudstone in the Retort Member, and prob ably also in the Meade Peak Member, is actually claystone or silty claystone. Some mudstone beds within the shale members, however, are properly classed as siltstone; for example, the detrital fraction of the basal bed of the Retort at Sheep Creek contains only about 30 percent clay (from analyses, assuming 26 percent A12O3 in illite), the basal bed at Hogback Mountain contains about 15 percent (from measurements on a thin section), and the entire lower half of the Retort at Sawtooth Mountain consists of siltstone that is not particularly argillaceous.

The silt in many silty claystones is concentrated in lenses and poorly defined and discontinuous laminae, and the clay in many clayey siltstones is concentrated in streaks; such uneven distribution is more the rule than the exception. Apatite pellets are also generally concentrated in laminae, lenses, and small groups, al though many pellets are isolated in the matrix.

CARBONATE ROCK

Most of the carbonate rock of the Phosphoria consists of thin interbeds of aphanitic dolomite. In relatively unweathered sections the colors are mostly grayish brown and pale brown colors having low chroma and values ranging from 3 to 6. The rocks are darker than dolomite of the Park City Formation but lighter in color than the shale and chert with which they are interbedded. Few of the dolomite beds are fissile, but otherwise there is little uniformity in thickness of bed ding. A larger proportion of the dolomite than of the mudstone is thick and very thick bedded.

Texturally, the dolomite of the Phosphoria resembles the aphanitic dolomite of the Park City Formation. Most of the beds are composed largely of a mosaic of dolomite anhedra that average about 20 microns in diameter. Dolomite rhombs about the same size as the

anhedra are scattered through several samples, and in a few samples, half the total dolomite consists of rhombs. One sample contains poorly defined circular areas of aggregates similar to those noted in some dolomite of the Park City. Carbonate fossil fragments make up 10 or 15 percent of several samples; at least some are replaced siliceous sponge spicules, which occur with siliceous spicules that are corroded and only partly replaced.

Either apatite or quartz silt may constitute more than 20 percent of the dolomite, but silty dolomite is more common than phosphatic dolomite. The apatite pellets are dark in color and have extremely irregular borders; they are generally evenly distributed throughout the dolomite. The quartz silt in most samples is also evenly distributed. The borders of nearly all the quartz grains are deeply corroded and invaded by dolomite. Little clay has been identified in thin sections of the dolomite.

The dolomite beds of the Phosphoria, especially those of the shale members, are particularly susceptible to weathering. They become soft and crumbly and some what lighter in value and stronger in chroma. The re sulting colors are light brown, yellowish gray, and weak yellowish orange. If the degree of weathering is ex treme, most of the dolomite is removed, and the in soluble residue forms a thin soft mudstone bed.

None of the few limestone beds of the Phosphoria has been studied microscopically, but in hand specimen they differ little in appearance from the aphanitic dolomite.

CHERTChert is both the most common and the most con

spicuous rock type of the Phosphoria Formation. Throughout much of the area the more massive beds of the chert members crop out in cliffs and combs that contrast with the soil-covered swales formed on the phosphatic shale members.

As seen in outcrop, the chert ranges in color from nearly black to white, in thickness of bedding from less than 0.02 foot to nearly 10 feet, and in character of bed ding from planar to very irregular and massive. The chert may consist almost entirely of microcrystalline quartz or it may contain considerable amounts of silt and clay, quartz sand, or much less commonly apatite, calcite, and dolomite, In unweathered sections the more argillaceous chert is generally dark colored and thin and even bedded, whereas the purer chert is lighter colored and more irregularly bedded.

The argillaceous chert is particularly susceptible to weathering. Where fresh, it is olive gray and light- brownish gray to grayish black, opaque, and dull or slightly resinous and has a splintery fracture; but on weathering it becomes weak yellowish orange and dusky yellow to white, porcelaneous or earthy, and much less


brittle and splintery in fracture. It may retain cherty- appearing streaks on the interior of beds, but otherwise the weathered chert, as seen megascopically, closely re sembles siltstone and has often been so described in the field. In thin section the only difference noted between specimens of weathered and unweatliered chert collected" from the same bed was a pervasive limonite stain in the weathered samples.

The purer chert ranges in color on fresh surfaces from brownish gray and medium gray to white. The luster is subvitreous and the fracture subconchoiclal. The thickness of bedding ranges from thin to very thick; where thin bedded, the individual beds, although con tinuous for long distances, commonly thicken and thin so that the bedding surfaces are midulant. Weathered surfaces range in color from light gray to weak yellow ish orange or pale brown, probably depending on the original content of pyrite and carbonaceous matter; but, in marked contrast to the argillaceous chert, even extreme weathering has little other effect.

The predominant constituent of the chert is micro- crytalline quartz. The average apparent grain diameter may be less than § microns or as large as 50 microns, but it is generally about 10 microns. The grain con tacts are sinuous and, in many instances, apparently gradational, and the extinction is markedly undulant. Both the nature of the contacts and the undulant ex tinction may be an aggregate effect (Folk and Weaver, 1952, p. 500). Although the grain size is generally rather uniform, many samples contain many poorly de fined roughly circular areas about 20 microns in diam eter, in which the grain size is less than 1 to 2 microns and within which are many inclusions. In addition to microcrystalline quartz, chalcedony is present in some thin sections as fibrous-appearing ribbons and festoons,, as spherulites, and as veins, but it rarely forms more than a small part of the total authigenic silica.

Clay commonly forms streaks, patches, and poorly defined laminae in the chert. The amount of clay, both in hand specimen and thin section, is difficult to deter mine, but comparison with the few A1 2O3 analyses of these cherts indicates that the clay content has generally been underestimated, in some beds by amounts of 10 or 15 percent of the total rock. Small quantities of angu lar quartz silt are scattered through much of the chert, and the detrital grains in sandy chert may be either evenly disseminated in the microcrystalline quartz or concentrated into sandy laminae. Scattered dolomite rhombs 10-20 microns in diameter are common, but they rarely constitute more than a few percent of the rock. Quartz pseudomorphs of dolomite are scattered through some thin sections. Calcite is rare, but where present it has generally replaced the microcrystalline quartz.

Iron oxide grains, 5-10 microns in diameter and pseudomorphic after pyrite, are scattered through nearly all thin sections of chert that have been examined. Most individual grains are cubes, many of which are com bined with octahedrons, but some are suggestive of pyritohedrons. The iron content of the chert beds that have been analyzed is remarkably high; total iron re ported as Fe2 O3 in the Rex Chert Member at Big Sheep Canyon averages about 4 percent, and most beds of the Tosi Chert Member at Sheep Creek contain about 3 per cent.

The amount of carbonaceous matter in the chert is small compared with that in the mudstone. Most beds that have been analyzed contain considerably less than 1 percent, and only one contains as much as 2 percent; yet those containing only a percent or so of carbonace ous matter are generally colored black or nearly black.

Apatite occurs as rounded grains of probable organic origin, as pellets, and as canal fillings and replacements of siliceous sponge spicules. The total amount of apa tite exceeds 4 or 5 percent in only a few chert beds that are either in or immediately adjacent to the phosphatic shale members.

The most striking feature of the chert as observed in thin section is the abundance of siliceous sponge spicules. The spicules in some thin sections are apparent in plane- polarized light; others are inconspicuous in transmitted light but may be seen readily in reflected light or by dark-field illumination; in other thin sections the spic ules are seen under crossed nicols as laths, ovals, and circles of quartz more coarsely crystalline than that of the matrix; in still others, only phosphatic axial- canal fillings can be seen. Nearly all the spicules are simple rods (oxea) that range from 0.01 to 0.8 milli meters in diameter. A few small diaxial and triaxial spicules have been noted; the rays are 10-20 microns in diameter and consist of isotropic apatite. The axial canals of the oxea are generally enlarged and have diameters as large as two-thirds the total diameter of the spicule. The enlarged canals may be filled with microcrystalline quartz, isotropic apatite, or, more rarely, glauconite. Carbonaceous matter is present in some canals (fig. 1157?), but clay fillings have not been identified. The fact that spicules having very different amounts of canal enlargement, spicules having quartz- filled canals, and spicules having apatite-filled canals may be seen in the same one field of view indicates that much of the solution of the spicules and filling of the canals took place before final accumulation of the sediment.

The apatite interiors of a few spicules seem to have formed by both the filling of enlarged canals and the replacement of silica in the canal walls. The apatite


interiors of the spicules consist of two distinct parts a central rod that is presumably the canal filling and a surrounding envelope that may have resulted from the replacement of silica adjacent to the central canal. How ever, most apatite spicule fillings and all glauconite fill ings that have been seen in thin sections are structure less and exhibit no evidence of actual replacement.

The oxea are oriented subparallel to the bedding and may also be crudely oriented linearly within the bed ding ; therefore, in some thin sections most of the spic ules are seen in cross section, in others they are seen in longitudinal section, and in a few they are seen in alter nating laminae of cross sections and longitudinal sections.

Nearly all the siliceous spicules consist of microcrystalline quartz, as described previously, but in at least one thin section they consist of chalcedony that in most spicules radiates from the central canal, although the chalcedony radiates from several centers within the body of several of the spicules. In cross section most spicules consist of microcrystalline quartz that is either unoriented or oriented with the C axis tangential to the spicule. Many, however, are spherulitic in cross section.

Figure 115^4 shows a relatively pure chert from the Tosi Member in which the spicules are extremely well preserved. The spicules are simple oxea, exceptionally large, some of which still retain the original concentric structure; some axial canals are moderately enlarged and filled with microcrystalline quartz. Some solution has occurred at spicule contacts, which is a feature un common in other samples. Figure 115# shows a slightly argillaceous and carbonaceovis chert from a bed that di rectly overlies the Retort Phosphatic Shale Member. Spicules are very abundant, but internal structure is not preserved. Figure 11561' shows an argillaceous chert, also from the Tosi Chert Member. The long, slender rods having high relief are apatite canal fillings, some of which are surrounded by a siliceous exterior. Figure 115Z> shows a relatively pure chert of the Tosi Member. No siliceous spicules can be seen, but the abundant ori ented apatite rods suggest that the rock was originally composed mostly of siliceous spicules.

The sequence of photographs illustrates why it is dif ficult to estimate the number of spicules. Spicules are apparent in the thin section shown in figure 115A be cause of the well-preserved internal structure, in figure 115# because of the carbonaceous matter in the matrix, in figure 115(7 because of the matrix material and the canal fillings, and in figure 115Z> because of the canal fillings. If no carbonaceous or argillaceous matter were present in the thin section shown by figure 115#, the spicules would be extremely difficult to detect, as suggested by the parts of the specimen that contain little

709-931 O 63 4

matrix material. The presence of spicules in the speci men shown on figure 115Z> could not be deduced at all if the canals had not been filled with apatite. The ab sence of observable spicules, therefore, does not mean that they were not present originally. If one takes these factors into consideration, then the most reasonable esti mate is that most of the silica in most of the chert was once in the form of spicules. Nevertheless, much matrix silica must be accounted for in some other manner.

M. W. de Laubenf els examined a number of thin sec tions of chert of the Phosphoria and stated (oral com munication, 1957) that the general aspect of the fauna is that of the class Demospongia. Many families and species are represented, but no more than could be found in a modern Demospongia assemblage. The few diaxial and triaxial spicules may be of the class Hyalospongia but could also belong to Demospongia. De Laubenfels found no microseres and no lithistid types.

MINOR ROCK TYPES

Rocks consisting of mixtures of clay, quartz sand and silt, apatite pellets, and sponge spicules occur in the middle of the Retort Phosphatic Shale Member at Hog back Mountain. The relative amounts of the constitu ents differ, forming rocks such as phosphatic cherty mudstone and sandy and muddy chert, but the general aspects of the rocks are much more similar than the range of names suggests. The finer grained constitu ents are generally concentrated in mudstone laminae, but some of the pellets, quartz sand, and spicules are distributed throughout. The coarse laminae may thicken, thin, or pinch out. Many of the siliceous spic ules have been partly or wholly replaced by isotropic apatite, and some of the mudstone has been silicified. The content of carbonaceous matter is low, generally only 1 percent or less, but it is sufficient to color the rocks medium and dark gray.

A rock type that occurs at the top of the Tosi Chert Member at several localities consists of mixtures of quartz silt, carbonate grains of silt size, and sponge spicules. Muscovite shreds and glauconite may also be present in small amounts. The carbonate, which is most commonly dolomite but in some beds is largely calcite, replaces partially or completely many of the siliceous spicules. The relative amount of the constituents is variable, the gross composition ranging from carbonatic chert to carbonatic mudstone to cherty carbonate rock. The rocks are generally thin bedded, and the color ranges from light gray to pale brown. One unusual variety of this rock type is found near the top of the Tosi at Lazyman Hill; the center of each bed of the thinbedded siltstone is cherty, whereas the upper and lower thirds are dolomitic, much of the dolomite clearly having replaced spicules.


7f -t ,^ .-*' ...!YJ - \-^^f»+ 4^<

jr.-" f -'i _ » £9 ? '-. m- r T ,._ii^gv^m^-w'UMuS^ ->.f.i--

FIGURE 115. Photomicrographs of chert from the Tosi Chert Member of the Phosphoria Formation. A, Relatively pure spicular chert from Hawley Creek, Idaho. Axial canals of spicules are enlarged and filled with microcrystalline quartz clouded by minute unidentified inclusions. Ordinary light. B, Spicular chert from Sliderock Mountain, Mont. Carbonaceous matter stains the argillaceous matrix black Ordinary light. C, Argillaceous chert from Sheep Creek, Mont. Slim dark rods are apatite canal fillings. Note the triaxial apatite spicules (h) and the faintly visible siliceous spicules (s) surrounding some rods. Ordinary light. D, Chert from Wadhams bprmg, Mont., showing apatite rods and dolomite rhombs. Ordinary light.

TRACE ELEMENTS

The trace-element content of black shale and phos phorite has been studied by Krauskopf (1955), and the trace-element content of phosphorite in the Phosphoria Formation, by Gulbrandsen (1960b and written com

munication). Gulbrandsen's results confirm those of Krauskopf. Gulbrandsen (written communication, 1961) found that the following elements are concen trated in the phosphorites of the Phosphoria by a factor of two or more over their crustal abundance: Silver,


zinc, vanadium, chromium, molybdenum, arsenic, anti mony, selenium, strontium, uranium, and rare earths. According to Gulbrandsen, strontium, uranium, and rare earths are probably in the apatite mineral; the other elements are those commonly concentrated in black shale (Krauskopf, 1955, p. 422), and they probably owe their concentration in the phosphorites to the carbonace ous matter that is also present.

Gulbrandsen (1960b) listed the abundance of these elements, in weight percent, in phosphorite of the Phosphoria from all parts of the western phosphate field as follows:

Element

AeAT __:_:_::_:::::::_______CrMo____ NdSb _ - _ - _____ - _ __SeSr _ ______U _____________ ___ ______________VYb_____-_--_______________________-Zn

Mode

0 0003004100303000700110090300103

Maximum

0 00302303030040071021100303

The semiquantitative spectrographic analyses on page 439 of samples from Sheep Creek are in accord with Gulbrandsen's results.

The occurrence of uranium in phosphorites of the western phosphate field has been summarized by Mc- Kelvey and Carswell (1956). The distribution of ura nium in phosphorites of the Meade Peak Member in southeastern Idaho has been studied by Thompson (1953, 1954), and the distribution of uranium in the Phosphoria of western Wyoming has been analyzed by Sheldon (1959). An excellent study of the geo chemistry of uranium in phosphorites has been pub lished by Altschuler and others (1958) . It suffices here to note that in Montana, as in Wyoming (Sheldon, 1959, p. 100), there is a direct relation between uranium and phosphate. The correlation coefficient of radiometrically determined uranium to P2O5, based on 40 samples selected at random from analyses of samples from the Retort Member in lots 1234, 1239, 1240, and 1299, is 0.668 (P<1 percent). The regression equation calculated from the same data is

wThere y is the weight percent uranium X 1,000, and x is the weight percent P2O5 .

CONTACT METAMORPHISM

Lowell (1955), described contact effects at several localities where igneous rocks have injected into or near Phosphoria strata. Most of the intrusives are andesitic

sills, but one is an apophysis from a quartz monzonite stock. In addition, he described Phosphoria strata in roof pendants or near the borders of large intrusive bodies, where metamorphic effects might be anticipated.

Near Mount Fleecer, nearly 4 miles northwest of Di vide, Mont., a one-half-mile wide prong of quartz mon zonite extends northward nearly 2 miles from a stock and occupies the axial part of an anticline. The prong is probably in conformable contact with the base of the Quadrant Formation and has replaced most of the un derlying carbonate rock of the Carboniferous and prob ably also of the older formations.9 At the land surface the base of the Phosphoria Formation on the east limb of the anticline is 300-900 feet from the intrusive con tact (Lowell, 1955, p. 723). If the contact between the quartz monzonite and the Quadrant is conformable, as appears likely, the stratigraphic distance from the Phosphoria to the intrusive is only 200-500 feet. Near the base of the prong, where an apophysis of quartz monzonite cuts across the Phosphoria and into the over lying Triassic strata, a series of thin lamprophyre sills described by Lowell (1955) occur within the Eetort Phosphatic Shale Member. Lowell (1955, p. 728) found that the light-gray phosphate rock and phosphatic shale within a few feet of the andesite sill are nearly white in thin section; much of the pelletal structure was destroyed, and the phosphate was converted to small irregular grains of apatite. Microscopic veinlets of quartz and spherulitic apatite occur in the shale, and most of the carbonaceous matter has been removed. Strata farther away are dark colored and appear to be unaltered.

Lowell noted that analyses showing only moderate amounts of P2O5 in the quartz monzonite seemed to con flict with field evidence indicating that 4 linear miles of the Phosphoria Formation had been engulfed by the quartz moiizoiiite. Analyses of the quartz monzonite from the vicinity averaged 0.22 percent P2O5 ; four anal yses from the apophysis averaged, 0.15 percent P2O5 ; and two analyses of the lamprophyre sills averaged 0.90 percent P2O5 . Grout and Balk (1934, p. 884) considered the small stock exposed south of Mount Fleecer to be a branch or offshoot of the Boulder batholith. Thus the P2O5 gained by assimilation of phosphate rock might have been so diffused by dissemination through the mag ma as to be undetectable in chemical analyses. The Retort Member in this region is 20-30 feet thick and contains an average of 20 percent P2O5 - Addition of this phosphate to a column of magma 1 mile high would raise the P2 O5 content of that magma only 0.08-0.11 percent. A thicker column of magma and lateral dis-

B Moore, G. T., 1956, Geology of the Mount Fleecer area, Montana: Indiana Univ.. Ph. D. thesis.


tribution by convection could easily combine to remove evidence of any contamination.

In the Highland Mountain area, where the Permian strata are located in the central part of a large roof pendant in quartz monzonite of the Boulder batholith, two andesite sills 4-9 feet thick intruded the Retort Member and a much thicker one intruded at the Quad- rant-Phosphoria contact. The lack of contact metamorphism in the Eetort Member and sharp contacts with the andesite sills indicate that the sills were injected at a fairly low temperature and without assimilation of phosphatic material; but shale has been brecciated at one of the contacts, and much quartz has been intro duced into some of the breccia fragments (Lowell, 1955, p. 725).

Lowell stated (1955, p. 725) : "Carbonaceous mat ter (?) may have been converted to fixed carbon by the heat of the intrusive to produce the black color of the phosphate rocks." This supposition coincides with our observations in sampling the beds of lot 1404 at a bull dozer trench cut below the zone of superficial weather ing. There a 14-foot sequence of phosphorite and shale is underlain by a much altered porphyritic sill, pre sumably andesite, of undetermined thickness. The beds in the lower part of the section are grayish black to dark gray, those in the upper part are somewhat lighter, and the shaly layers at the top of the interval are medium to yellowish gray. All equipment used during the sam pling became unusually dirty, much as they would from working in graphitic schists, and remained so thereaf ter. Although the dark color of these rocks, which ap pears in thin section to be a black matrix for quartz and collophane, suggests a fairly high content of carbona ceous material, the 14 samples averaged only 1.68 per cent carbonaceous matter. It seems probable that much of the carbonaceous material occurs in the form of graphite, which would not be detected in the chemical analyses.

Lowell (1955, p. 730) described sills and dikes in the Maiden Rock mine, a few miles southeast of the Fleecer Mountain stock and southwest of the main mass of the Boulder batholith. The dikes and sills are much altered but had a composition apparently similar to the quartz monzonite of the large igneous bodies. Contacts with the phosphatic shales of the Retort Member are locally irregular, and small inclusions of the shale occur as much as 2 inches within the dike. Although Lowell found physical evidence of some assimilation, chemical analyses of two dike rocks showed only 0.18 and 0.22 percent P2O5 , respectively.A small andesitic sill occurs in the phosphatic shale

at the South Boulder section (lot 1365), where, as Lowell (1955, p. 733) concluded, the induration of the

shale units next to the sill was the only metamorphic effect.

At Jack Canyon (lot 1218) in the Madison Range, a 4-foot andesite porphyry sill occurs near the base of the Retort Member. The sill is underlain by a thin layer of sandy phosphorite containing pellets and oolites in a darker matrix; the phosphorite in turn grades downward into fine-grained phosphatic sandstone con taining abundant quartz overgrowths. In the sand stone within a few inches of the intrusive, much of the apatite in the matrix between quartz grains has been recrystallized to clusters of very fine grained (3-10 mi crons) clear apatite (fig. 116). The quartz overgrowths are characteristic of the Shedhorn Sandstone and ap parently formed much earlier than recrystallization of the apatite. In the phosphorite layer some of the quartz grains appear to have been corroded and partly re placed by apatite. These features seem to be related directly to the heat from the sill.

At Kelley Gulch (lot 1249) a dike of probable dacitic composition has intruded the Retort Member. It ap pears to be about 30 feet thick but is exposed only in the hand trench and may be a very irregular body. The rock is strongly banded, chiefly dark gray to black hav ing streaks of white, and shows a well defined flow struc ture. It contains very abundant angular inclusions of dark chert and mudstone of the Phosphoria Formation 1-40 mm across, around which the flow bands are draped. In thin section many smaller inclusions are visible; they include quartz, sandy phosphatic chert containing abundant sponge spicules, phosphate pellets, and quartz-siltstone fragments. The groundmass is submicrocrystalline and contains euhedral phenocrysts of plagioclase and strongly corroded quartz. No con tact effects with either the country rock or the inclusions have been noted, and the fine texture of the rock matrix and the well-defined flow structure indicate that the rock was forcefully injected at a low temperature and probably at shallow depth.

STRATIGRAPHY

MEADE PEAK PHOSPHATIC SHALE MEMBER

The Meade Peak Phosphatic Shale Member of the Phosphoria Formation was named by McKelvey (Mc- Kelvey and others, 1956, p. 2845) for Meade Peak in southeastern Idaho. In the type area the member con sists of about 200 feet of phosphorite, carbonaceous mudstone, phosphatic mudstone, and dark dolomite and limestone. It is overlain by the Rex Chert Member of the Phosphoria and underlain by a tongue of the Gran deur Member of the Park City Formation. Most of the commercial phosphorite in the western phosphate field is produced from the Meade Peak. In southwestern


FIGURE 116. Very sandy phosphorite from top of phosphatic sandstone bed (Rt-10) underlying 4-foot andesitp(?) porphyry sill at Jack Canyon (lot 1218), Madison Range. A, ordinary light; B, crossed nicols. Note in B that much of the apatite is recrystallized, appar ently by heat of intrusion, although apatite rims around quartz grains remain isotropic. Apatite farther from intrusive is not recrystallized. q, quartz grains; a, apatite.

Montana, as in southeastern Idaho, the Meade Peak Phosphatic Shale Member is characterized by phospho rite, black shale, and dark carbonate rock. In Montana the Meade Peak is thinner and less extensive and has been economically less important than the Retort Phos phatic Shale Member, which occurs higher in the sec tion. Mining of the Meade Peak Member, however, was started in the Centennial Mountains in 1956, and the member is potentially more important economically than the Retort Member over much of the southern part of the area.

The Meade Peak Phosphatic Shale Member is under lain by the Grandeur Member of the Park City Forma tion throughout southwestern Montana, with the excep tion of that part in the vicinity of Quadrant Mountain, Yellowstone National Park. At Quadrant Mountain the underlying beds have been assigned to the Quadrant Formation, although the uppermost 40 feet are probably equivalent to beds included elsewhere in the Grandeur. The lower contact of the Meade Peak is normally sharp and planar, although at a few localities, such as Quad rant Mountain, phosphatic sandstone grades downward into nonphosphatic sandstone (Condit and others, 1928,

p. 188). Although the contact between the Grandeur Member of the Park City and the Meade Peak Member seems conformable where seen in outcrop, the regional stratigraphic relations show that the older rocks must have been eroded in the eastern half of the area prior to deposition of the Meade Peak. The strongest evi dence of such erosion is the absence east of the Ruby River of the upper terrigenous beds of the lower mem ber of the Park City or of any rock types that could be their shoreward equivalent. Thus the basal bed of the Meade Peak oversteps the upper part of the lower part of the Park City to the east. In the southwestern part of the area, there is little or no evidence of either overstepping or pre-Phosphoria erosion.

The contact of the Meade Peak with the overlying Rex Chert Member of the Pliosphoria is also sharp and distinct; the soft phosphorite and flaky mudstone of the Meade Peak contrast with the hard platy thin- bedded chert of the basal part of the Rex. In much of the southern part of the area, the contact is marked by a thin phosphorite bed that is commonly skeletal and locally cherty. In the Gravelly Range where the Meade Peak is overlain by a tongue of the lower member of


the Shedhorn Sandstone, the highest phosphorite bed is separated from the relatively nonphosphatic Shedhorn by a bed of phosphatic sandstone that is included in the Meade Peak.

The distribution and thickness of the Meade Peak Member in southwestern Montana are shown in figure 117. Very generally, the Meade Peak extends north- northwestward into Montana as a tongue, thicker on the west than on the east, to Big Hole Canyon, the northernmost locality where the member has been found.

The eastern edge of the tongue roughly coincides with the Madison Valley, and the western edge is between Big Sheep Canyon, Mont., and Hawley Creek, Idaho. The thickest section of the member is at Big Sheep Can yon, where it is nearly 30 feet thick. Other thickness maxima are at Sawtooth Mountain, where the member is 16 feet thick, and in the Centennial Mountains, where it is as much as 18 feet thick. An area of thinning extends southeastward from the Sheep Creek-Dalys Spur region.

113°

45'

111°

EXPLANATION 25


Isopleth of percent P2Os in memberContour interval 5 percent

FIGURE 117. Isopach map of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation. X, control point showing measuredthickness ; A, control point, data approximate.


In the Centennial Mountains where Honkala has mapped the Permian rocks in detail and measured a number of closely spaced sections, the Meade Peak Member changes radically in thickness within short distances and is absent in two areas (Honkala, 1953, pis. 2 and 4). One area in which the member is absent is between i/2 and 1 mile in diameter, which is too small to show on the thickness and facies maps; the other area is on the extreme west end of the area mapped by Hon kala, and its extent, although not known, is assumed to be small.

The great distance of the Meade Peak Member at Quadrant Mountain from other exposures of the mem ber and the necessitated sharp change in the trend of the zero isopach line in both Montana and Wyoming (Sheldon, 1957, fig. 13) indicate that the member at Quadrant Mountain may be part of an isolated lens. Evidence of such lensing is reported by Condit and others (1928, p. 189), who state that at the Quadrant Mountain section the beds now assigned to the Meade Peak Member consist of more than 3 feet of phosphorite, whereas at Bannock Peak 3 miles to the southeast, the same unit is an inconspicuous phosphatic sandstone.

The areal variation in lithologic character of the Meade Peak Member is shown in figure 118. The nota ble features are (1) the area of combined carbonate, apatite, and mud near Lima which coincides with the area of maximum thickness of the member, (2) the apatite-rich band around the edge of the area in which the member occurs, and (3) the change in character within short distances in the Gravelly Kange. Litho logic variation similar to that in the Gravelly Range would probably be found near the edge of the member in other areas if sections were as closely spaced. The distribution of carbonate rock in the Meade Peak Mem ber is further shown in figure 119, which was constructed by totalling the thickness of all beds of carbonate rock in the member at each locality. The map shows a strik ing local concentration of carbonate rock west of Lima.

The Meade Peak Member can be divided into two parts in the Tendoy Mountains, the Snowcrest Range, and the Centennial Mountains. These are a lower phosphorite, which locally contains minor interbeds of mudstone and dolomite, and an upper phosphatic mudstone consisting of interbedded mudstone, phosphatic mudstone, phosphorite, and, locally, dolomite. The lo cation of the boundary between the two units is uncer tain in the Tendoy Mountains, and the units cannot be correlated northward to the Dillon area with any con fidence. Nevertheless, the phosphorite in the northern sections is probably the continuation of the lower phos phorite, as is suggested by the occurrence of an upper

mudstone at Sheep Creek, Dalys Spur, and Big Hole Canyon.

LOWER PHOSPHORITE

The lower phosphorite of the Meade Peak ranges from 0 to 12 feet in thickness in the Centennial Moun tains, is nearly 9 feet thick at Big Sheep Canyon, and is nearly 7 feet thick at Sawtooth Mountain (fig. 120).

The lithologic character of the lower phosphorite is somewhat variable (fig. 121), but everywhere, with the possible exception of Sheep Creek, it has either been deposited from or reworked by currents. The minor constituents of the bed range from conglomerate in the Gravelly Range to sand in the central part of the area and to mud in the Lima region.

Honkala (1953, p. 18) found that the lower phos phorite in the Centennial Range is split by lenses of sandy carbonate rock and carbonatic sandstone that pinch out within remarkably short distances. For ex ample, a lens 4 feet thick may pinch out in less than 10 feet along strike.

The upper phosphatic mudstone consists of relatively barren mudstone that contains thin interbeds of phos phorite and phosphatic mudstone. It is present throughout the Tendoy Mountains, where it is as much as 20 feet thick, the Snowcrest Range, where it ranges from 1 to 10 feet in thickness and the Centennial Moun tains, where it is locally more than 7 feet thick. It disappears eastward by thinning of the mudstone and consolidation of the phosphatic layers and cannot be distinguished from the basal phosphorite east of the Ruby River. The upper phosphatic mudstone could not be traced with certainty northward from the Tendoy Mountains, but it may be represented by mudstone in the upper half of the Meade Peak at Dalys Spur, Sheep Creek, and Big Hole Canyon.

The character of both the mudstone and the apatite is the same wherever the upper phosphatic mudstone could be identified. The mudstone in the eastern Snow- crest Range may contain a smaller proportion of clay than the equivalent mudstone farther west, but the average grain size of the silt fraction is everywhere about 25-30 microns. The interbedded phosphorites are generally dark colored and pelletal and show little evi dence of current action, with the exception of the thin phosphorite at the contact with the Rex chert. At several localities this phosphorite bed contains quartz sand, phosphatic skeletal fragments, and well-formed and rounded pellets that indicate current activity.

The Meade Peak Member in the Gravelly Range changes considerably in character within short dis tances, although the phosphorite itself is everywhere the current-deposited variety. At Canyon Camp more


112°

EXPLANATION

Apatite Carbonate (acid soluble other than apalite)

Patterns used singly in class I areas; combined in class n and in areas

FIGURE 118. Lithologic character of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation. X, control point; A, controlpoint, data approximate.

than half the member consists of limestone, which is absent at Warm Springs Creek only 3 miles distant; most of the member at Lazyman Hill is composed of a chert bed 4 feet thick that is absent at Warm Springs Creek 6 miles northwest and at Alpine Creek 3 miles south; half the member at Alpine Creek consists of chert

and dolomite-pebble conglomerate that is not present in quantity in any of the neighboring sections.

Equivalents of the Meade Peak Member have not been identified with certainty in the Permian section in the Madison Eange; if any rock equivalents exist, they are probably insignificant in thickness, as is indi-


113° 112° 111°

MONTANA WYOMING

FIGURE 119. Thickness of beds of carbonate rock in the Meade Peak Phosphatic Shale Member of the Phosphoria Formation.point showing measured thickness in feet; A, control point, data approximate.

X, control

cated by the marked thinning of the member in the Snowcrest and Gravelly Ranges. The manner in which the member terminates northward is not known, but there is no reason to believe that any significant part of the Permian section near Melrose or in the Three Forks area is equivalent to the Meade Peak farther south.

From the type area of the Meade Peak Phosphatic Shale Member in southeastern Idaho northward to Fall Creek in the Caribou Range of Idaho, the upper part of the Meade Peak passes into chert.and the lower part passes into dolomite containing minor chert (R. P. Shel- don, oral communication, 1957). The Meade Peak of

southwestern Montana is thus probably equivalent to only the central part of the member in southeastern Idaho.

REX CHERT MEMBER

The Rex Chert Member of the Phosphoria Formation was named by Gale for Rex Peak in the Crawford Mountains, Rich County, Utah (Richards and Mans field, 1912, p. 684). McKelvey and others (1956, p. 2847) pointed out that, although the strata near Rex Peak that were originally termed Rex consist largely of dolomite, subsequent usage has sanctioned the name as applying to the main chert unit of the Phosphoria. McKelvey therefore retained the name Rex but redesig-


113° 112° 111°

EXPLANATION

IsopachContour interval I foot; not con

toured where unit is less than 5 feet thick

- -25

Isopleth of percent P2 O 5 in unitContour interval 5 percent

FIGURE 120. Isopach map of the lower phosphorite of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation. X, controlpoint showing measures thickness in feet; A, control point, data approximate.

nated the type locality of the member as the Phosphoria Gulch area in southeastern Idaho and restricted the name to the dominantly cherty interval between the Meacle Peak Phosphatic Shale Member of the Phos phoria and the nonresistant mudstone and cherty mudstone at the top of the formation. As thus redefined, the Kex Chert Member at the type locality ''consists of a basal zone about 20 feet thick of nonresistant chert and

carbonate rock overlain by about 125 feet of resistant chert 1 ' (McKelvey and others, 1956, p. 2847).

The Kex Chert Member in southwestern Montana consists chiefly of bedded chert and locally contains minor amounts of cherty mudstone, phosphorite, and carbonate rock. It overlies the Meade Peak Phosphatic Shale Member of the-Phosphoria Formation, underlies the Fraiison Member of the Park City Formation, and


113° 112° 111°

327

MONTANA WYOMING

EXPLANATION

Nodules Oolites Skeletal fragments

Pellets are present at a/I localities

FIGURE 121. Character of apatite grains in the lower phosphorite of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation.

intertongues eastward with the lower member of the Shedhorn Sandstone.

Both the upper and the lower contacts of the Rex Chert Member are generally sharp and conformable, but in some of the places where the Rex is directly over lain by sandstone, the upper contact is gradational. In parts of the Centennial Mountains and the Gravelly Range, the Rex Chert Member intertongues with the

Shedhorn Sandstone so that it is both overlain and underlain by sandstone.

The Rex Chert Member is approximately 80 feet thick in the central and western Snowcrest Range (fig. 122; from there it thins eastward, northward, and westward. The edge of the member could not be located accurately, but the Rex may extend as far eastward as the Gallatin River and as far northward as 10 or 20 miles south of


113° 112° 111°

MONTANA WYOMING

-20-


EXPLANATION

Isopleth of total thickness of mudstone beds in the Rex

Contour interval 5 feet

FIGURE 122. Isopach map of the Rex Chert Member of the Phosphoria Formation, x, control point showing measured thickness in feet;A, control point, data approximate.

Butte. The Rex is only about a foot thick in the west ernmost sections; so, it probably ends a few miles west of Kelley Gulch. It has not been identified at Hawley Creek.

A certain regularity exists in the vertical distribution of rock types within the member at several localities. A complete section consists of thin- and even-bedded dark-colored somewhat argillaceous chert at the base; the chert grades upward into lighter colored irregularly

bedded chert that in turn grades upward into light- colored very thick bedded chert. The complete sequence is found at only a few localities; that at Hogback Moun tain is the best example. The thin- and even-bedded chert is present at the base of the member in nearly all the thicker sections. The basal few feet are generally grayish black or dark gray, but higher in the member the color is lighter. The irregularly bedded chert over lies the evenly bedded chert at many Ipcalities, but at


a few localities, such as Wadhams Spring, very thick, bedded chert rests directly on the evenly bedded type. At other localities, Sliderock Mountain for example, ir regularly bedded chert continues to the top of the mem ber.

Variation of the proportions of the chert types at different localities results in regional differences in aspect of the Rex. Thus, most of the member at Little Sheep Creek and Wadhams Spring consists of thin- and even-bedded chert, whereas most of the member in the eastern Snowcrest Range consists of irregularly bedded chert. Most of the Rex at Sheep Creek is thin- and even-bedded, whereas at Big Hole Canyon it is very thick bedded. The sections near Lima that are composed dominantly of the thin- and even-bedded chert also con tain interbedded cherty mudstone that makes up 10 or 15 percent of the member. Cherty mudstone occurs in the Rex also at Canyon Camp, but it cannot be traced to any of the neighboring sections.

A phosphatic bed occurs in about the middle of the Rex Chert Member in the Tendoy Mountains and the western Snowcrest Range. It is more than a foot thick in places and ranges from phosphatic chert to phospho rite in lithologic character. The apatite grains show the effects of current action, and in most localities the bed consists of mixtures of well-formed and rounded pellets, oolites, and skeletal fragments.

The Rex Chert Member ends eastward by thinning and by intertonguing with the lower member of the Shedhorn Sandstone. The facies change from chert to Sandstone is most convincingly shown by comparing the section at Sliderock Mountain with that at Alpine Creek (fig. 12). The Rex probably ends to the north in part by pinching out, but the upper half of the Rex in the Tendoy Mountains may be the equivalent of the lower part of the Franson in the Dillon area.

The lower part of the Rex Member at Big Sheep Can yon in the Tendoy Mountains consists largely of mudstone and cherty mudstones that intertongue northward and eastward with chert more typical of the Rex.

The presence of the mudstone and cherty mudstone and also of a thin phosphorite bed in the Rex Member in the Tendoy Mountains suggests that at least the lower half of the Rex in that region may be the equiv alent of part of the Meade Peak Phosphatic Shale Mem ber of southeastern Idaho. Such a facies change would be in accord with the regional relationships, for R. P. Sheldon (oral communication, 1957) stated that the lowest part of the Rex is formed by progressively older rocks northward in Idaho.

RETORT PHOSPHATIC SHALE MEMBER

The Retort Phosphatic Shale Member of the Phos- phoria Formation was named by Swanson (in

McKelvey and others, 1956, p. 2850) for Retort Moun tain in the Blacktail Mountains about 10 miles south of Dillon, Mont. Although natural exposures exist in the type locality, in 1959'the member was best exposed in a bulldozer trench just east of the road crossing the divide between Small Horn Canyon and Sheep Creek drainages. This is the Sheep Creek locality, lot 1234, of this report. The Retort is the D member or unit of earlier reports.

The Retort Member at the type locality consists of 60 feet of pelletal phosphorite, phosphatic mudstone, and mudstone mostly grayish and brownish black and contains 11.5 percent P2O5 (or nearly 30 percent apatite) and nearly 9 percent carbonaceous matter. It rests conformably on sandstone of the Franson Member of the Park City Formation, and at the top grades up ward through a phosphatic sandstone bed 0.8 foot thick into the upper tongue of the Shedhorn Sandstone.

The Retort Member is underlain by sandstone and carbonate rock of the Park City Formation in the Mel- rose and Dillon areas and west of Lima, but elsewhere it is underlain by a tongue of the lower member of the Shedhorn Sandstone. Throughout much of south western Montana, the contact of the phosphorite and dark mudstone of the Retort with the underlying nonphosphatic light-colored rocks is gradational through a thickness of generally 2 feet or less, but at Cave Creek, it is gradational through as much as 6 feet. Elsewhere, as at the type section, the contact is sharp and conformable.

The Retort is overlain by a tongue of the Shedhorn Sandstone from West Fork of Blacktail Creek to Hog back Mountain in the Snowcrest Range, at Sheep Creek, and locally in the Melrose area. It is overlain by noncarbonaceous mudstone and cherty mudstone of the cherty shale member of the Phosphoria Formation west of Lima, but in nearly all other areas, it is overlain by the Tosi Chert Member. The upper contact is com monly gradational through an interval of a foot or less. Locally in the eastern part of the area, mudstone of the Retort grades upward into the Tosi Chert Member through an interval of interbedded chert and mudstone

c5

as much as 20 feet thick, and where such gradation oc curs, only the part that is dominantly mudstone is in cluded in the Retort.

The Retort Member is about 85 feet thick along an axis trending northeast from Big Sheep Canyon to Hogback Mountain. From the axis the member thins to the east, north, and west (fig. 123). It pinches out between Sappington Canyon and the Three Forks sec tion in the northeastern part of the area, and although the edge cannot be located elsewhere, it probably ex tends southeast from Three Forks to a short distance


113° 112° 111°

-20-EXPLANATION


Isopleth of percent P2 O 5 in memberContour interval 5 percent

FIGURE 123. Map showing thickness and P2O5 content of the Retort Phosphatic Shale Member of the Phosphoria Formation. X, controlpoint, showing measured thickness in feet; A, control point, data approximate.

east of Cinnabar Mountain. The member extends at least 45 miles north of Butte to the Elliston and the Garrison-Avon districts and perhaps as much as 60 miles to the northwest in the Garnet Range near Drum- mond. The westward extent of the member is not known, but the rapid thinning; from Big Sheep Canyon to Hawley Creek and the oolitic nature of the phos phorite at Hawley Creek both suggest that the Retort was not deposited much farther west than the Beaver- head Range.

The lithologic character of the Retort- Member is shown in figure 124. Apatite is not anywhere dominant, but it is most abundant in two belts; one belt extends northward from Lima through Dillon and roughly coin cides with the area of maximum thickness of the mem ber, whereas the other is in the eastern part of the field, where the member is thin. This distribution is some what similar to that in the Meade Peak Member, in which apatite is abundant both in the area where the member is thickest and nearer the feather edge.


The Ketort Phosphatic Shale Member can be divided into three facies on the basis of the character of the phosphorite. The facies are (1) The nodular-phos phorite facies, characterized by dark argillaceous pelletal phosphorite containing 10-20 percent of compound nodules; (2) the pelletal-phosphorite facies, containing dark pelletal phosphorite but no nodular, colitic, or

skeletal beds; and (3) the marginal facies, characterized by oolitic and skeletal phosphorite. The marginal facies is found generally east of the Euby Eiver, near the Jefferson Kiver, and in the Beaverhead Eange; the pelletal facies is found in the area between the Beaver- head and Ruby Eivers; and the nodular facies is found in the Tendoy and Pioneer Mountains. The member in

45

113° 112°

MONTANA WYOMING

EXPLANATION

Apatite

Patterns used singly in class I areas; combined i class H andffl areas

Carbonates and carbon aceous mattar (acid insoluble other than apatite)

FIGURE 124. Lithologic character of the Retort Phosphatic Shale Member of the Phosphoria Formation. X, control point.

332

part of the northern Madison Range consists of a local pelletal f acies located in the area of the marginal f acies. The overall f acies distribution, then, is as follows: The marginal f acies occurs in the eastern and westernmost parts of the area; it grades through the pelletal f acies into the nodular f acies, which occurs in the area where the member is the thickest.

The gradation between the pelletal and nodular f acies consists of an increase in the number of nodule-bearing beds and in the degree of induration of the nodules. In the Sheep Creek section, for example, few nodules were apparent in the freshly exposed rock, but weather ing over a period of several years revealed compound nodules similar in size and distribution to those found in sections farther west, that consisted of pellets some

what better cemented than those in the surrounding rock.

Although the coincidence is far from perfect, the car bonate rock (fig. 125), mostly dark aphanitic dolomite, is concentrated in the nodular phosphorite f acies of the Retort Member. The content of the carbonaceous matter (fig. 126) shows no obvious relation to f acies. The Big Sheep Canyon and Kelley Gulch sections of the Retort are both located in the nodular phosphorite facies, but the rocks at Big Sheep Canyon are highly carbonaceous and average 8.4 percent carbonaceous mat ter, whereas those at Kelley Gulch, although dark in color, average only 1.2 percent.

The three facies are further compared in figure 127, iu which frequency diagrams were constructed in the

MONTANA WYOMINGx°

10 0 10 20 30 MILES l , , , , l l i l

FIGURE 125. Percent carbonate rock in the Retort Phosphatic Shale Member of the Phosphoria Formation. X, A, control points.


113° 112° 111°

333

FIGURE 126.- -Content of carbonaceous matter in the Retort Phosphatic Shale Member of the Phosphoria Formation. X, control pointshowing percent carbonaceous matter in member.

same manner as those in figure 105. The nodular phos phorite facies consists mostly of phosphatic mudstone and contains some carbonate rock and carbonatic mudstone but little high-grade phosphorite. The pelletal phosphorite facies, as exemplified by the Sheep Creek and Hogback Mountain sections, also consists largely of phosphatic mudstone; it contains practically no cal careous and dolomitic beds but does include some high- grade phosphorite. In the Melrose district, however, pelletal phosphorite makes up a large part of the facies. The marginal facies does not have the well-formed phosphatic-mudstone mode present in the other two facies but contains a larger proportion of both car bonate rock and phosphorite. Details of the frequency

709-931 O 63 5

distributions differ, depending, of course, on which localities are selected to typify the different facies, but the general relations discussed above are probably com mon to the facies as a whole.

According to McKelvey (1949, p. 272), the beds com posing the Meade Peak Phosphatic Shale Member of the Phosphoria Formation in southeastern Idaho are remarkable for their great lateral continuity. For ex ample, the lower phosphate bed, the "cap" limestone, the "false cap" limestone, and many other beds can be traced from the Fort Hall region of Idaho southward to the Utah border, a distance of about 75 miles. In the Retort Member in Montana, however, detailed cor relations can be made among only a few localities, andy


APATITE

Nodular Phosphorite Facies(lot 1224)

Not contoured because of small number of analyses

APATITE

.CALCITEAND

DOLOMITE

Pelletal Phosphorite Facies (lots 1234 and 1299)

APATITE

DOLOMITE

Marginal Facies DOLOMITE (lots 1318, 1362, and 1365) UULUMI 11

EXPLANATION

Sample density, in percent

0-5 5-10 >10

FIGURE 127. Mineral composition of rocks in three facies of the Retort Phosphatic Shale Member of the Phosphoria Formation.

in general, individual beds of the Retort are undoubt edly less extensive than those of the Meade Peak Mem ber in southeastern Idaho.

The Retort Phosphatic Shale Member in the type section at Sheep Creek, Mont., consists of three parts: the lower unit, 26 feet thick, consists mostly of interbedded phosphorite and phosphatic mudstone; the mid dle unit, a little more than 15 feet thick, consists of nonphosphatic carbonaceous mudstone; the upper unit, 19 feet thick, consists of phosphorite and phosphatic mudstone similar to that in the basal unit. The upper phos phatic unit either pinches out OT grades into mudstone to the west, so that at Cedar Creek the Retort consists of only the lower two units (pi. 24).

The three units that compose the Retort Member at the type locality at Sheep Creek could not be traced with confidence either northward, eastward, or south ward. The member at Kelley Gulch consists of three parts: The lower 30 feet is composed of interbedded phosphorite, phosphatic mudstone, mudstone, and dolo mite ; the overlying 14 feet consists of barren mudstone; and the uppermost 10 feet is composed of mudstone that contains several interbeds of phosphorite. These three- units are possibly the equivalents of the three units at the type section and at Dalys Spur, but this correlation is by no means certain, for the mudstone unit at Kelley Gulch is intruded by a dike that may have displaced some strata. Correlating the Retort at Kelley Gulch with that at Big Hole Canyon by way of the section at Cave Creek suggests that the upper phosphatic zone at Kelley Gulch is thicker and more phosphatic and that the middle mudstone thins eastward in a manner similar to the changes occurring from Dalys Spur to Sheep Creek. The Retort Member at Big Hole Canyon would thus consist of the upper and the lower phosphatic zone, as at Kelley Gulch, which are not separately recogniz able in the absence of the middle mudstone. On the other hand, correlation by way of the Greenstone Gulch section rather than the Cave Creek section suggests that nearly all the Retort at Big Hole Canyon is the correla tive of only the lower phosphatic zone at Kelley Gulch. The Cave Creek section, like that at Kelley Gulch, is cut by igneous intrusions, and much of the member at Greenstone Gulch is sheared and faulted; therefore, no clear choice can be made between the two possible corre lations. The Retort Member at Big Hole Canyon is sim ilar to that in the Melrose area, but it contains more dolomite and has phosphorite that is slightly lower in grade. The difficulty of correlating southward from the type area of the Retort is evident from plate 24.

The Retort Member in the Tendoy Mountains con tains much carbonate rock in comparison with the mem ber in the type locality, and much of the phosphorite is


nodular. The upper one-third or two-thirds of the member consists of black mudstone that contains little apatite. Most of the carbonate rock pinches out north eastward from the Tendoy Mountains into the Snow- crest Range; the phosphorite in the Snowcrest Range is not nodular but is almost entirely pelletal, and phos phorite beds occur at the top of the member (fig. 91). In the Snowcrest Range, the Retort changes abruptly in thickness and character within short distances; the lower half of the member is highly phosphatic at the West Fork of Blacktail Creek, barren at Sawtooth Mountain, phosphatic again at Hogback Mountain, and absent at Canyon Camp. These apparently erratic changes in the lower part of the section result probably from the fact that the line of sections crosses and re- crosses facies strike; the interval actually passes from interbedded phosphorite and mudstone to barren mudstone and finally pinches out. The chert and sandstone in the middle of the Retort at Hogback Mountain seem to pinch out to the west rather than to grade into mudstone; but to the east in the Gravelly and Madison Ranges, they may be represented by chert and sand stone at the base of the Retort and at the top of the lower member of the Shedhorn Sandstone.

Whatever the details of the eastward change may be, the shale and phosphorite of the Retort in the Gravelly Range appear to be the equivalent of only the upper part of the member in the Snowcrest Range. The correla tion of the member from Alpine Creek in the Grevelly Range to Indian Creek in the Madison Range is simple and direct; although the member at Indian Creek con tains somewhat more phosphorite, it would not seem out of place if substituted in the section at Alpine Creek.

Farther south in the Gravelly Range and in the Cen tennial Mountains, the upper part of the Retort Mem ber consists of nonphosphatic mudstone that is probably equivalent to the basal beds of the Tosi Chert Member in the northern Gravelly Range and may be a tongue of the cherty shale member of southeastern Idaho.

The member also includes progressively younger rocks from Indian Creek to Shell Canyon in the Madi son Range (pi. 22) ; thus at Shell Canyon, the upper contact is probably higher in the section than it is in the northern Gravelly Range section and is probably also higher than in the Snowcrest Range section. Be tween Shell and Jack Canyons, the Retort intertongues with the lower part of the Tosi Chert Member, and the contact at Jack Canyon is therefore lower in the sec tion than at Shell Canyon.

The correlation of the Retort from Big Hole Canyon to South Boulder Creek (pi. 19), a distance of 38 miles across facies strike, has been made largely by analogy with the line of sections shown in plate 21,

where the lower half of the Retort pinches out to the east and the upper half passes only to a minor extent into chert. Thus the Retort at South Boulder Creek is probably equivalent to the upper part of the mem ber at Big Hole Canyon, and the top of the member at South Boulder Creek is probably little if any lower in the section than it is at Big Hole Canyon. An alternate possibility that the upper part of the member in the Big Hole Canyon-Melrose area passes northeastward into chert and that the entire Tosi Member at South Boulder Creek is therefore the equivalent of the upper part of the Retort near Melrose has been advanced by Rooney (1956b) and is logical on the basis of the line of sections he presents. However, the correlation from the Snowcrest Range to the Madison Range and from there northward along the facies strike to Sappington Canyon supports the correlation presented herein.

Northward and eastward from South Boulder Creek, the mudstone of the Retort grades into chert so that at Three Forks the beds equivalent to the Retort consist of bedded chert containing thin phosphatic beds.

The changes in both the thickness and the lithologic character of the Retort from the Lima region westward can only be surmised inasmuch as at Hawley Creek most of the interval between the Tosi Chert Member of the Phosphoria and the Franson Member of the Park City is covered. The only phosphorite exposed at Haw- ley Creek consists of oolitic rock that rests directly on the Franson Member of the Park City Formation, but the covered interval is littered with muddy-chert and cherty-mudstone float. Thus, most of the Retort may pass westward into cherty mudstone, and the Retort it self at Hawley Creek is probably thin.

The stratigraphy of the Retort Member in southwest ern Montana is summarized as follows: The lower half of the member pinches out east of the type section and is absent in the eastern half of the area. The upper half thins eastward and northeastward and passes into chert in the Three Forks area. Westward from the type area of the member, the upper half grades into mudstone and probably passes into cherty mudstone farther west. The lower half remains phosphatic far ther to the west than the upper half.

Details of the relation of the Retort Phosphatic Shale Member in Montana to the Retort in western Wyoming and southwestern Wyoming are uncertain because of the distance 50 miles between exposures on the north and the south sides of the Snake River Plain and the Yellowstone Plateau. The upper part of the Permian section in the Gros Ventre Range of Wyoming and at Red Creek near the southern border of Yellowstone National Park consists of a thin Retort Phosphatic Shale Member overlain by about 50 feet of the Tosi


Chert Member, which is in turn overlain by a tongue of the Sheclhorn Sandstone (Sheldon, 195T, pi. 13; Mc- Kelvey and others, 1956, fig. 2) ; the sequence is very similar to that found east of the Ruby River in Mon tana. The contact between the Retort and Tosi Mem bers rises in the section west of the Gros Ventre Range, so that in the southern Teton Range of westernmost Wyoming, the upper tongue of the Shedhorn Sandstone rests directly on the Retort Member, the upper part of which is probably younger than any of the Retort in Montana. The same relation is suggested by the ob servation that the upper contact of the Retort rises somewhat in the section south in the Gravelly Range.

According to R. P. Sheldon (oral communication, 1957) the Retort Member in the Big Hole Range of eastern Idaho is underlain by a highly phosphatic sand stone that can be traced eastward at least as far as the Gros Ventre Range of western Wyoming. In Montana, the beds underlying the Retort are generally not highly phosphatic, and the phosphatic sandstone of western Wyoming is possibly the equivalent of the sandstone in the middle of the Retort at Hogback Mountain. The lower half of the Retort in the Lima and Dillon areas would then be older than any beds included in the Retort in Wyoming or eastern Idaho. These inferred relation ships are illustrated in figure 93.

TOSI CHERT MEMBER

The bedded chert that overlies the Retort Phosphatic Shale Member constitutes the Tosi Chert Member of the Phosphoria Formation. The member was named by Sheldon (in McKelvey and others, 1956, p. 2851) for Tosi Creek in the southern end of the Gros Ventre Range of western Wyoming, where it consists of 33 feet of bedded chert that overlies the Retort Member of the Phosphoria and underlies the upper tongue of the Shedhorn Sandstone.

In the westernmost exposures of Permian strata in southwestern Montana, the Tosi Chert Member consists of 90-150 feet of bedded chert that overlies mudstone of the cherty shale member or mudstone and phosphorite of the Retort Member and underlies calcareous mudstone of the basal part of the Dinwoody Formation. To the east, the Tosi passes into and intertongues with the upper member of the Shedhorn Sandstone. In the region from Big Hole Canyon southward to the central and eastern Snowcrest Range, the Tosi Chert Member and Shedhorn Sandstone are intertongued throughout the entire interval between the Retort and the Din- woody Formation. East of the Ruby River most of the Tosi occurs as a distinct unit, 40-80 feet thick, between the underlying Retort and the overlying upper tongue of the Shedhorn Sandstone.

Figure 128 shows the regional variation in the thick ness of beds assigned to the Tosi. The irregular thin ning of the member to the east results in part from thinning of the interval but mostly from intertonguing with the Shedhorn Sandstone.

Vertical sequences of chert types that occur in the Tosi in parts of the area are similar to those in the Rex Member. In the Gravelly Range the basal few feet of the Tosi consists of argillaceous thin- and evenly bedded chert that is dark gray or brownish gray where unweathered. This chert passes gradually upward into thin and irregularly bedded chert that is less argillace ous and lighter colored. Still higher in the section, the thickness of bedding is about the same, but the undulant bedding surfaces are less distinct and the upper most 10-30 feet of the chert has a massive appearance. In the Madison Range the chert is also argillaceous and thin- and even-bedded at the base of the member and contains many mudstone partings that are less evident upward. The chert is lighter colored, less well bedded, and variably sandy in the upper part of the section.

No such regularity in the vertical sequence of the chert is apparent in the rest of southwestern Montana. Most of the chert at both Sheep Creek and Wadhams Spring is argillaceous and thick- and even-bedded. At Big Sheep Canyon it is highly argillaceous and, for the most part, thin- and even-bedded. But at Hawley Creek, nearly all the chert is relatively pure and very thick bedded.

Although carbonate in amounts exceeding more than a few percent is uncommon in chert of the Tosi, both calcite and dolomite occur near the top of the section at several localities in carbonatic siltstone and chert. Discrete beds of dolomite, generally cherty, occur in the Three Forks area and in parts of the Centennial Moun tains. Geodal vugs lined with calcite occur at Shell Canyon in the Madison Range.

A sequence of about 10 feet of sandy, dolomitic, and locally cherty siltstone beds that occur at the top of the Periman section in the Gravelly Range and the eastern Snowcrest Range has been included in the Tosi Chert Member, although it could nearly as logically have been placed in the Shedhorn Sandstone. It has not been placed in the basal part of the Dinwoody because the beds commonly contain both chert and glauconite, which are typical minerals of the Permian rocks.

CHERTY SHALE MEMBER

The Tosi Chert Member and the Retort Phosphatic Shale Member at Big Sheep Canyon are separated by nearly 60 feet of hard thin-bedded olive-gray mudstone that weathers into platy fragments. Similar mudstone, 25 feet thick, occurs in the upper part of the Tosi Chert.


113° 112° 111°

337

MONTANA WYOMING

FIGURE 128. Isopach map of the Tosi Chert Member of the Phosphoria Formation. X, control point showing measured thickness in feet;A, control point, data approximate.

It contains very little apatite or carbonaceous matter. The contact of the cherty shale member with the under lying soft fissle and flaky grayish-black carbonaceous and slightly phosphatic mudstone of the Eetort is sharp, planar, and distinct. Although the hard platy mudstone does not seem to be cherty at Big Sheep Canyon, it closely resembles much of the rock of the cherty shale member of the Phosphoria Formation in the Fort Hall region in southeastern Idaho described by McKelvey and others (1956, p. 2849). Continuity with the cherty shale member of Idaho cannot be demonstrated, but the facies position of the mudstone of Big Sheep Canyon is such that continuity might be expected; that is, the gen eral basimvard trend in the phosphate field is from

chert to cherty mudstone, and there is no reason to ex pect a reversal of the trend between the Lima region and the type area of the cherty shale member. For these reasons, the name cherty shale member is tenta tively applied to the platy light-colored nonphosphatic and. noncarbonaceous mudstone at Big Sheep Canyon. Cherty mudstone is also present at Little Sheep Creek near Lima and may constitute most of the covered in terval beneath the Tosi Chert Member at Hawley Creek; these rocks are also included in the member.

The cherty shale member at Big Sheep Canyon, passes eastward and probably northward and westward into chert of the Tosi Member. To the west, both the upper and lower contacts of the member may be lower


in the section, and if the covered interval at Hawley Creek is composed of cherty mudstone, it is probably the equivalent of the Retort Member at Big Sheep Canyon.

LOCALIZATION OF EXPLOITABLE PHOSPHATE DEPOSITS

Most phosphorite from the western field is treated either with sulfuric acid to produce fertilizer or in an electric furnace to produce elemental phosphorus. The sulfuric acid process requires rock having a minimum P2O5 content of 31 percent, whereas an electric furnace requires rock having a minimum of about 24 percent P2O5 . Acid-grade rock in beds as thin as 3 feet can be mined profitably if other factors are highly favorable, but rock of lower grade must occur in considerably thicker beds to be exploited successfully. The P2O5 content of phosphatic rock can be increased by as much as 4 or 5 percent, to the required grade, if the greater thickness of the minable zone, favorable mining condi tions, and favorable location offset the expense of beneficiation. The effects of rock type and of stratigraphic relations on the localization of deposits of minable thickness and grade are analyzed briefly here.

As discussed on page 310, the phosphorites can be grouped into two broad types: (1) those that were sorted and winnowed by currents, and (2) those that were not. Phosphorites of the first group contain little carbonaceous matter and little or no clastic matrix; ce ment, if present, is generally chert or apatite. Quartz- sand grains may be admixed. In places, beds of cur rent-washed phosphorite thicken and thin markedly, as the apatite sand had apparently been piled into banks and bars. At two localities in the western phosphate field in the Centennial Mountains and near Bear Creek in the Caribou Range of Idaho (Sheldon, 1957, p. 26) phosphorite of this type forms beds 12 feet thick, but at both places the beds thin markedly within short dis tances.

Phosphorites that do not show evidence of significant current activity are generally argillaceous and carbona ceous and are commonly interbedded and interlaminated with mudstone. The phosphorites and interbedded mudstones maintain their thickness and character over a considerable area.

Considering the characteristics of the two groups of phosphorites, one might expect to find acid-grade beds of minable thickness in units containing current-washed phosphorite, but because of thickness changes expect able in this type of rock, such deposits would be of rela tively small extent. Beds of sandy phosphorite amen able to beneficiation might be found, but they would probably not be sufficiently thick or widespread to jus tify the expense. On the other hand, one would not

expect to find acid-grade beds of minable thickness in sections composed mostly of the phosphorite that shows little evidence of current activity, but furnace-grade beds of minable thickness might occur, depending on the abundance and thickness of mudstone and dolomite interbeds. Any such furnace-grade deposits would probably be of large extent.

In southwestern Montana, current-washed phospho rite is found principally in the lower part of the Meade Peak Member in the Centennial, Gravelly, and Snow- crest Ranges and in the marginal facies of the Retort Member. Acid-grade phosphorite of the current- washed variety has been mined from the Meade Peak Member in the Centennial Mountains by J. R. Simplot Company; the high-grade bed there is as much as 11 or 12 feet thick, thins to 4 or 5 feet within short distances, and is absent locally. Acid-grade rock of minable thickness has not been found elsewhere in the area dis cussed in this report, but it is at least possible that the basal bed of the Meade Peak Member may thicken suf ficiently between measured sections in the Snowcrest and southern Gravelly Ranges to form small exploit able deposits. Approximately 12 feet of sandy cur rent-washed phosphorite is present in the Retort Mem ber at Cinnabar Mountain, but the rock would require beneficiation for furnace use. Its presence suggests that other small deposits might be found near the east ern margins of the Retort Member, but the available data are not encouraging.

In the area considered in this report, the phosphorite in the upper part of the Meade Peak Member and in the pelletal and nodular facies of the Retort Member is of the variety that shows little evidence of current activity. Furnace-grade rock has been mined from the Retort Member in the Melrose area; nearly the entire member is mined, but some beneficiation is required to raise the P2O5 content of the ore to the minimum grade required for the furnace charge. A minable thickness of furnace-grade rock has not been found in the member elsewhere in the area. South of Melrose mudstone inter beds become thicker and more abundant in the Retort. The upper part of the Meade Peak Member is both too thin and too low in P2O5 content to be an adequate source of furnace-grade rock.

SHEDHOBN SANDSTONE

GENERAL CHARACTER AND DISTRIBUTION

The Shedhorn Sandstone has been defined as the dominantly sandy strata of Phosphoria age that occur within Yellowstone National Park and adjacent parts of southwestern Montana and northwestern Wyoming (Cressman and Swanson in McKelvey and others, 1956, p. 2852). The type section (locality 1362 of this report)


FIGURE 129. Type locality of Shedhorn Sandstone, northeast wall of Indian Creek Canyon, 0..3 mile below mouth of Shedhorn Creek, Madison Range, "fid Dinwoody Formation: psu, upper member of Shedhorn Sandstone ; Ppt and Pprt, Tosi Chert and Retort Phosphatic Shale Tongues of Phosphoria Formation ; ps|, lower member of Shed- horn Sandstone. Part of lower member of Shedhorn Sandstone, the Grandeur Tongue of Park City Formation, and top of Quadrant Formation hidden by trees.

is on the north side of Indian Creek in the Madison Range, Mont., one-quarter of a mile below the mouth of Shedhorn Creek (fig. 129).

At the type section the Shedhorn consists of an upper member ranging from 60 to 80 feet in thickness and a lower member 48 feet thick. The two members are separated by a tongue of the Phosphoria Formation that is nearly 50 feet thick, and the lower member is divided into two parts by a tongue of dolomite of the Franson member of the Park City Formation that is 7l/2 feet thick. Both members of the Shedhorn contain thin beds of chert that may be tongues of the Tosi and Rex Members of the Phosphoria, but, in the absence of clear

evidence for this correlation, they are included in the Shedhorn.

West of the type locality the upper member intertongues with the Tosi Chert Member, and the lower member intertongues with the Franson Member of the. Park City Formation and the Rex Chert Member of the Phosphoria. The sandstone tongues are identified with the name Shedhorn as far as they can be traced. The sandstone of the Shedhorn is distinguished from sandstone of the Quadrant Formation and of the Gran deur Member of the Park City Formation by the pres ence of apatite pellets and skeletal fragments and by the abundance of chert grains. Similar-appearing sand stone occurs in the Franson Member of the Park City Formation in the Tendoy Mountains and near Dillon, but the facies distribution (fig. 144) indicates that the<- sand came from a different source area and is not later ally continuous with the type Shedhorn.

The thickness and distribution of the Shedhorn Sand stone in southwestern Montana is shown in figure 130. Tongues of the upper member extend northward to the Garnet Range and southeastward to the Gros Ventre Range of Wyoming. The lower member has not been identified north of the area shown in figure 130, but in western Wyoming, tongues extend to the southern end of the Wyoming Range (R. P. Sheldon, oral communi cation).

LITHOLOGY

SANDSTONE

The Shedhorn Sandstone shows remarkable uniform ity in grain size, sorting, composition of the detrital fraction, color, thickness of bedding, and hardness throughout the area; however, the amount and type of cementing material and the amount of glauconite differ widely from place to place.

The results of thin-section size analyses of samples of Shedhorn Sandstone are summarized in table 2 and in figure 131. The median diameter (uncorrected for sectioning) of 60 percent of the samples is in the very fine sand class, and the remainder is in the fine-sand class. The coarsest median diameter of any of the analyzed specimens is only 0.18 mm., and fine- and very fine grained sandstone undoubtedly constitutes most of the Shedhorn. Some medium-grained and finely pebbly sandstone has been seen, however, particularly in the lower part of the Shedhorn. The sandstone of the Shedhorn is extremely well sorted; the coefficient of sorting (So) of nearly 60 percent of the samples is less than 1.25, and that of the least well-sorted sample is only 1.37.

The sorting coefficients are plotted against the mean phi diameters in figure 132. The regression coeffcient,


112°

A 20Permian rocks disconformably overlain by

Ellis Group (Jurassic) north of line

WYOMINGX 62 \

\ \ IPermian rocks disconformably overlain by > JDinwoody Formation (Triassic) east of line |

FIGURE 130. Isopach map of the Shedhorn Sandstone. X, control point showing measured thickness in feet; approximate.

control point, data

r, for the 28 pairs is 0.4316, which is significant (P< 0.05 >0.01). The sorting coefficient /So varies inversely with Md$ ; that is, the sorting tends to improve as the grain size decreases.

The terrigenous fraction of the sandstone consists almost entirely of quartz and chert; feldspar grains are extremely scarce. The detrital quartz is very simi lar in character to that of sandstone of the Park City Formation, as the grains are mostly subangular and equant, although many of the coarser ones are subrounded and about 10 percent are elongate. Much less than one-fourth of the quartz grains show prominent strain shadows; these grains are generally crowded wTith bubble inclusions. The great majority of the grains

either have straight extinction or show slight straining; inclusions are not common, but wrhere present they consist of unoriented rutile needles, apatite, tourmaline, and planes of bubble inclusions.

Chert grains make up generally about 10 percent of the total sand-size fraction but may be present in amounts as much as 20 percent. This percentage is in marked contrast with those of sandstone of the Gran deur Member of the Park City and of the Quadrant which generally contain about 2 percent chert grains. The chert grains are similar in size to the associated quartz but are commonly somewhat better rounded. Most are shades of gray and brown, but a few are color less or nearly so. In marked contrast with most sand-


DIAMETER, IN PHI 234

DIAMETER, IN PHI 234

100

Z 80u O ir u Q.u 60

40

20

All samples 3.21 Lower half 3.45

Mean So All samples 1.23 Lower half 1.24

Mean Md<f> Lined area 3.02

Mean So Lined area 1.26

0

Upper member of Shedhorn Sandstone. Curves for all 17 samples fall within stippled area; all 7 samples from the lower half and 4 samples from the upper half fall within lined area

B. Lower member of Shedhorn Sandstone. Ten samples fall within lined area.

*"" on

U Oo:uQ.u 60

_iO > 40u >

$=1 ?osZ>o

n

Url*

1

Sn

L35 3.28 1.31

L54 3.87 1.52 L8 4.55 1.50

I

IT

AJ /f

fijf

299-L35\J

f

4T

4

1 ,i f* // // tii_/

^1299-L54 X\^

7

// /

' /

//

*

f

1299-L8

C. Grandeur Member of Park City Formation D. All samples

FIGURE 131. Summary of the size distribution data of Permian sandstone. Curves not corrected for sectioning. Md<i>, phi median diameter;So, Trask sorting coefficient.

stone of the Shedhorn, sandstone of the upper tongue of the formation in the Melrose area contains almost no detrital chert.10

Apatite, generally constituting 4-8 percent of the rock, occurs as yellowish-brown isotropic sand-size pellets, as bone or shell fragments, and less com monly as large roughly oval grains of uncertain origin (fig. 133). The pellets are subrounded and well rounded and are about the same size or slightly larger than the associated detrital quartz grains. Many contain nuclei of quartz or chert grains, frag-

10 Rooney, L. F., 1956, A stratigraphic study of the Permian forma tions of part of southwestern Montana : Indiana Univ., Ph. D. thesis, p. 19.

ments of siliceous sponge spicules, or glauconite grains. Few oolites or micro-crystalline pellets have been seen in the sandstone, a surprising fact con sidering the abundance of both in sandy phosphorite. The large roughly oval grains of uncertain origin have a maximum length of several millimeters and range in shape from rather irregular grains to well-formed ovals. Some contain large quantities of silt and clay inclusions, others are crowded with sponge spicules replaced by apatite, and still others seem to be aggregates of indistinct pellets. The larger grains may represent both intraformational fragments and faecal pellets.


EXPLANATION

Upper part of Shedhorn Sandstone

Lower part of Shedhorn Sandstone

Grandeur Member of Park City Formation

1.0

FIGURE 132. Relation between coefficient of sorting (So) and phi median diameter (MdQ). Data from unconnected thin-section sizeanalyses. Lines of best fit based on Shedhorn samples only.

Apatite also occurs in some samples as yellowish- green isotropic rims, about 5 microns thick, around quartz-sand grains. The boundary between the coat ing and the grain is generally somewhat irregular. Quartz overgrowths may surround the apatite rim.

Glaucoiiite grains are conspicuous in most of the sandstone in the western edge of the formation but are uncommon elsewhere. A few samples contain as much as 20 percent glauconite, but most glauconitic beds con tain only 1 or 2 percent. The microcrystalline aggre gates are green and yellowish green; weathered grains are light-brownish green. Morphologically the glauco nite occurs as: (1) somewhat irregular grains and ag

gregates, whose form depends partly on the shape of the surrounding grain; (2) smooth, rounded, generally equant grains; and (3) fractured grains having one curved edge and one or two straight edges. All three types may be present in the same thin section. Had- cling (1932, p. 95, 99) considered the first type as hav ing formed at the site of accumulation and the second type as having been transported. Many glauconite grains contain inclusions of pyrite or of iron oxides pseudomorphic after pyrite.

Heavy-mineral separations were made of five sam ples of the upper tongue of the Shedhorn from Sheep Creek and Wadhams Spring. The Shedhorn is so uni-

343

FIGURE 133. Photomicrograph of sandstone from the base of the upper member of 'the Shedhorn Sandstone at Sheep Creek showing apatite pellets having nuclei composed of quartz grains, an apatite skeletal fragment with apatite deposited about the exterior, and a large oval apatite grain of uncertain origin. Thin films of apatite surround many quartz grains, and the rock is cemented with microcrystalline quartz. Bed from which sample was taken contains 3.0 percent PaO5 (7% percent apatite). Ordinary light.

form in texture and composition of the light detrital material both areally and stratigraphically that there is no reason to expect any major differences in the assem blages of heavy accessory minerals; therefore, the val ues for these two localities are probably applicable in a general way to the formation as a whole.

The nonopaque accessory minerals consist almost en tirely of the stable species-tourmaline, zircon, and rutile and very minor amounts of sphene, anatase, gar net, and apatite. Leucoxene is the only common opaque mineral. The heavy minerals that could be separated formed only 0.01 percent of the total sample, even though the efficient centrifuge method was used.

The samples were separated into size fractions before centrifuging. The separates coarser than 88 microns contained too few heavy mineral grains for a reliable count, so the relative amounts of the various species in the total heavy mineral assemblage could not be deter mined directly. The size distributions of zircon and tourmaline in one of the samples from Sheep Creek as determined from the counts and the sieve data were therefore plotted, and their relation to the total size distribution of the sample was compared with the the oretical relation developed by Rubey (1933) and the empirical relation found by Rittenhouse (1943) (fig. 134).

According to Rubey, if quartz and zircon are de posited together, quartz having a diameter of 4 phi should have the same frequency as zircon having a diameter of 4.5 phi, and quartz having a diameter of 2.5 phi should have the same frequency as zircon hav-

120

DIAMETER, IN PHI

FIGURE 134. Comparison of size distributions of zircon and tourmaline with that of total sample; bed Us-124, lot 1234.

ing a diameter of 3.3 phi. According to Rittenhouse, the zircon grains should be 0.9 phi unit smaller than the hydraulically equivalent quartz. The difference between the cumulative curves of quartz and zircon in figure 134 is thus smaller than one would expect, and nearly all the zircon is probably in the size fractions that were counted. Tourmaline should be 0.2 phi unit smaller than the hydraulically equivalent quartz (Rit tenhouse, 1943), and the corresponding size distribu tion curve for tourmaline has been plotted in figure 134. If the corrected thin-section size analysis is correct, all but 10 percent of the tourmaline should be in the size fractions that were counted. The count data for leucoxene have not been plotted, but the curve would coincide approximately with that of tourmaline, the coincidence implying both a specific gravity and a total size distribution similar to those of tourmaline.

The weight frequencies of the species in the total heavy-mineral fraction of the sample were then cal culated on the assumption that 10 percent by weight of both tourmaline and leucoxene was in the coarse frac-


Rutile 3 percent

FIGURE 135. Composition by weight of heavy accessory minerals in bed Us 124, lot 1234.

tions that had not been counted. The result plotted in figure 135 shows that leucoxene forms half of the total heavy minerals, and that tourmaline and zircon each constitute one-fourth. Rutile makes up only a few percent, and garnet, apatite, and anatase are present in negligible quantities.

The tourmaline was studied in some detail, because in orthoquartzites containing limited suites of accessory minerals, the comparison of varietal frequencies of the same mineral species offers the best means of detecting changes in provenance. Tourmaline has been studied successfully in this manner by Krynine (1946). In the Shedhorn Sandstone, however, the heavy mineral con tent is so small and the number of tourmaline varieties so large that the error for any one varietal frequency cannot be restricted to within a useful limit. Further more, the types are gradational, so that counts cannot be repeated with precision, and the varietal classifica tion itself is so subjective that it is unlikely that any other person classify the tourmaline in exactly the same manner. The tourmaline data given in figures 136 and 137 should therefore be considered semiquaiititative only.

The tourmaline consists of six major color varieties pink, green, brown, olive, blue, and multicolored of which the brown and olive varieties are by far the most common. Pink and green tourmaline are more abun dant in the less than 44-microii fraction than in the 88- to 62-micron fraction, whereas brown tourmaline is more abundant in the coarser than in the finer size frac tions. The frequencies of the color varieties in the Shedhorn samples are plotted in figure 136 and are com pared with Weaver's data for samples from the Park

City and Shedhorn Formations (Weaver, 1955, p. 184). Cressman has seen Weaver's samples and believes that most of the differences shown 011 figure 136 result from subjectivity of the method rather than from actual dif ferences between the assemblages. For example, the grains classified as colorless by Weaver would prob ably have been classified in this study as pink, pale olive, or pale blue.

Most of the tourmaline is subrounded (fig. 137 A). Rounded grains occur only in the sizes coarser than 44 microns, and angular ones occur only in sizes finer than 44 microns. Angular idiomorphic grains are present only in the fraction containing sizes finer than 44 mi crons, where they constitute about 20 percent of the tourmaline (fig. 137 B}. About half of the angular idiomorphic tourmaline contains inclusions similar to those called carbonaceous by Krynine, (1946, p. 69), but tourmaline containing few or no inclusions is most prevalent in the other roundness classes (fig. 137 C).

Most of the angular idiomorphic grains are pale pink and contain the so-called carbonaceous inclusions; these were probably derived ultimately (and perhaps di rectly) from a low-rank metamorphic source (Krynine, 1946, p. 68). The rounded tourmaline grains in the two larger size fractions contain practically no.inclu sions and are brown, green, or olive; these were prob ably derived ultimately from a plutonic source (Kry nine, 1946, p. 68), although the rounding suggests that they have passed through several sedimentary cycles. The angular xenomorphic grains are mostly blue, olive, and green and contain few inclusions; they may have been derived in part from pegmatites (Krynine, 1946, p. 68). The subrounded type is the most prevalent in all size fractions, and although brown and olive grains having few inclusions are most common, the group in cludes grains of all colors and some grains having both bubble and carbonaceous inclusions. Both the rounding and the large number of varieties indicate that this group was derived from preexisting sediments.

Zircon, which constitutes about one-fourth of the heavy detrital minerals, consists of 80 percent colorless and 20 percent pale-pink grains. The surfaces of more than 90 percent are pitted, and about half of each color type are equant and half are elongate. More than 90 percent of the zircon grains are appreciably abraded; half of these are rounded or subrounded. Weaver (1955, p. 184) found that in sandstone of the Quadrant, and of the Grandeur Member of the Park City 91 per cent of the zircon grains are colorless and 40 percent are equant. Our observations are similar to his.

Rutile makes up about 3 percent of the heavy min erals; both reddish-brown and brown varieties were noted. All grains of garnet, which constitutes less


A, Grandeur Member of Park City Formation, 44 to 74 micron fraction; compositeof 5 sandstone samples from Kelly Gulch and Sheep Creek.

B, Quadrant Formation, 44 to 74 micron fraction; composite of 4 sandstonesamples from Sheep Creek and Wadhams Spring.

C, Dinwoody Formation, less than 44 micron fraction; composite of 3 calcareousmudstone samples from Sheep Creek

D, Upper member of Shedhorn Sandstone, 62 to 88 micron fraction; composite of3 samples from Sheep Creek and Wadhams Spring.

E, Same samples as in D, 44 to 62 micron fraction. F, Same samples as in D, less than 44 micron fraction.

Data for A and B from Weaver, 1955, p. 184

FIGURE 136. Relative abundance of tourmaline color varieties.

00

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than 1 percent of the heavy minerals, are deeply cor roded. One euhedral diagenetic crystal of anatase was seen.

The sand is cemented with microcrystalline quartz (chert), quartz overgrowths, or, less commonly, cair- bonate. The microcrystalline-quartz cement is similar in grain size and character to that in bedded chert. In places it forms nearly 50 percent of the rock but gener ally only 10 or 15 percent. Siliceous sponge spicules are present in many of the sandstone beds that contain large amounts of microcrystalline quartz, so the actual amount of interstitial chert cement is much less than first appears. Most chert cement contains grains of iron oxide pseudomorphic after pyrite, and pyrite itself lias been seen in several unweathered specimens. The detrital quartz grains in some thin sections of the sand stone are rimmed by chalcedony, which is in sharp contact with interstitial microcrystalline quartz; in other thin sections, the quartz grains are surrounded by irregular overgrowths of quartz in optical continuity with the grain that seem to grade outward into the microcrystalline quartz; in still other thin sections, contacts between microcrystalline quartz and the grains are sharp and distinct.

Unweathered specimens of chert-cemented sandstone fracture across the grains and are quartzitic in appear ance, but weathering disaggregates the chert, and the rock becomes somewhat friable.

Nearly all sandstone seen in surface exposure is weath ered the pyrite has been oxidized to iron oxides and the glauconite has turned olive brown and brown. The resulting rock has a low chroma with TR hues and a moderate to high value pale-brown, yellowish-brown, yellowish-gray, and very pale orange colors (fig. 138). Unweathered sandstone occurs in the interior of some beds, where pyrite and glauconite are unoxidized, the rock is extremely hard and somewhat vitreous appear ing, and the color is grayish blue.

Nearly all the sandstone is thick- or very thick bedded and hard. More-weathered beds tend to be medium hard.

CHERT

Chert occurs as thin beds, lenses, and bodies of ex tremely irregular shape. Petrographically it differs little from the lighter colored chert in the Eex and Tosi Members of the Phosphoria Formation; many of the chert beds may be thin tongues of these members.

DOLOMITE

Dolomite forms a very minor part of the Shedhorn Sandstone. In the lower member, the dolomite is mostly aphanitic and very sandy, similar to dolomites of the Franson Member of the Park City Formation. Most

dolomite in the upper member of the Shedhorn is sandy and bioclastic, and several beds are microcoquinas formed of brachiopod fragments. The cementing ma terial is anhedral dolomite having an average crystal size of 25-50 microns. The dolomite of the upper part of the Shedhorn is thick bedded and similar in color to the adjacent sandstone.

STRATIGRAPHY

LOWER MEMBER

At Indian Creek in the Madison Kange, the type locality of the Shedhorn, the lower member of the Shed- horn Sandstone is denned as the sandstone beds that underlie the Retort phosphatic shale tongue of the Phosphoria and overlie the Grandeur Member of the Park City Formation. The abundance of chert grains and the presence of small amounts of apatite pellets and skeletal fragments distinguish the sandstone from that of the Grandeur Member of the Park City Forma tion and from that of the Quadrant Formation.

The interval at the type section from the top of the lower member to the base is about 55 feet thick, but it includes a tongue of the Franson Member of the Park City 7y2 feet thick; so, beds actually assigned to the lowest member have a total thickness of about 47 feet. Several chert beds totaling nearly 10 feet in thickness are present in the lower member; they may be tongues of the Rex Chert Member, but they cannot be so identi fied with certainty. The original description of the lower member gave the thickness as 17 feet (Cressman and Swanson, in McKelvey and others, 1956, p. 2852), but the lower part of the type section has since been restudied.

The member is more than 25 feet thick in much of the eastern Centennial Mountains, the Snowcrest Range, and the northern Gravelly Range (fig. 139).

The lower member thins westward from the Gravelly Range by intertonguing with the Franson Member of the Park City Formation and the Rex Chert Member of the Phosphoria Formation (pi. 21), The most ex tensive tongue of the lower member lies directly beneath the Retort Phosphatic Shale Member of the Phosphoria and separates it from the Franson Member of the Park City. The tongue is present at the West Fork of Black- tail Creek and may extend as far west as Wadhams Spring. Another extensive tongue of the lower member occurs at the top of the Rex Chert Member and extends westward to Sawtooth Mountain.

The lower member abruptly thins eastward from the type area. The thinning probably takes place partly by eastward overlap at the base and partly by thinning


lOOr

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VALUE

Sheep Creek (lot 1234)

N Y YR

HUE

0-3 4-8 CHROMA

FIGURE 138. Color of Shedhorn Sandstone. Number and letter symbols are from National Research Council "Rock-Color Chart" (Goddard and others, 1948).


113° 112° 111°

349

MONTANA WYOMING

45

FIGURE 139. Isopach map of the lower member of the Shedhorn Sandstone. X, control point showing measured thickness in feet; A, controlpoint, data approximate.

of beds throughout the interval. Conglomeratic beds at the top of the member at Pulpit Rock may indicate removal of some beds at the top.

The lithologic character changes little, either areally or stratigraphically. Several sandstone beds in the Gravelly and Madison Ranges, the Centennial Moun tains, and the Three Forks area contain scattered chert and dolomite pebbles, whereas the sandstone farther west does not; but the texture of the sand-size material remains remarkably constant. Other regional differ ences are (1) the prevalence of dolomite cement in the Gravelly Range but of siliceous cement, both as chert and as overgrowths, in the Madison Range and the

709-931

Centennial Mountains, and (2) the presence of at least a few glauconitic beds to the west of the Ruby River but not to the east.

The lower member of the Shedhorn is the equivalent of the Rex Chert Member and the Franson Member of the Lima region and thus of the Rex of southeastern Idaho. The lower member seems to be younger than any of the Meade Peak of Montana, but if the upper contact of the Meade Peak is lower in the section north of its type area, then the basal part of the lower part of the Shedhorn may well be the equivalent of the upper part of the Meade Peak of the Phosphoria Gulch sec tion of southeastern Idaho.


UPPER MEMBER

At the type locality of the Shedhorn Sandstone, the upper member consists of the sandstone and chert interbeds, lenses, and nodules that lie between the Tosi Chert Member of the Phosphoria Formation and the Din- woody Formation of Triassic age. Near the type sec tion the thickness of the upper member varies from 64 to 81 feet within a few hundred yards along the outcrop. Tongues of the upper member extend westward to Lima and the Pioneer Mountains, northwestward to the Garnet Range near Garrison, and southward to the Gros Ventre Range of Wyoming.

The upper member is overlain by the Dinwoody throughout the Madison and Gallatin Ranges, but in

much of the Gravelly Range it is separated from the basal part of the Dinwoody by about 10 feet of glauconitic, locally cherty, dolomitic mudstone that is con; sidered to be a tongue of the Tosi. From the Ruby River westward to Red Rock Valley and the Pioneer Mountains, the Tosi Chert Member and the upper member of the Shedhorn are intertongued throughout the interval between the Dinwoody Formation and the Retort Phosphatic Shale Member of the Phosphoria Formation.

The isopach map of the upper member of the Shed- horn (fig. 140) shows the total thickness of beds actually assigned to the member; it therefore shows the approx imate total thickness of sandstone in the interval be-

MONTANA WYOMING

Permian rocks partly removed by pre- Dinwoody erosion east of line

20 30 MILES

FIGURE 140. Isopach map of the upper member of the Shedhorn Sandstone. X, control point showing measured thickness in feet; A, controlpoint, data approximate.


tween the Retort Member of the Phosphoria and the lowermost Mesozoic strata. Reentrants in the iso- pachs define a northward-trending zone through the Ruby Valley in which the upper member is thin and that divides the member into two parts. West of this zone, sandstone of the upper member extends fingerlike southward from Butte through most of the Snowcrest Range; it is interbedded with chert throughout the en tire post-Retort and pre-Dinwoody interval. East of the Ruby River, the upper member of the Shedhorn generally overlies the Tosi Chert Member and occupies only the upper part of the post-Retort interval, although sandstone directly overlies the Retort at Quadrant and Cinnabar Mountains. The upper mem ber extends as a wedge westward from the type area in the Madison Range to the Ruby River, where it apparently merges with the upper part of the south ward-extending sandstone (pi. 20).

The upper member of the Shedhorn, like the lower member, is rather uniform in character. Nearly all the sandstone is well sorted in 17 analyzed samples So averages 1.23. The mean phi diameter of the 17 sam ples averages 3.21 (0.108 mm); it is thus somewhat finer grained than the lower member, for which the average mean phi diameter is 3.02 (0.123 mm) (fig. 131A). Some coarser grained beds having mean phi diameters ranging from 3 to nearly 2.5 (0.125 to 0.177 mm) characteristically occur in the uppermost 40 feet of the member. Brachiopod shells and shell fragments are present in the uppermost part of the member in several sections but are virtually absent elsewhere. Cross- bedding has been noted only in the uppermost beds and only in the Gravelly Range.

The upper member differs laterally in the type of cement and in the glauconite content. Generally the sandstone is glauconite bearing and cemented by chert west of the Ruby River, is glauconite free and cemented by quartz overgrowth east of the Madison River, and is intermediate in character in the Gravelly Range. In the Three Forks area the member is mostly nonglau- conitic, and much of the sandstone is cemented by dolo mite. Although chert-cemented sandstone is not as common in the Madison and Gallatin Ranges as to the west, chert lenses, nodules, and beds are more common.

A striking feature of the Permian rocks in the area dominated by the Shedhorn Sandstone is the presence of abundant columnar bodies of sandstone, cherty sand stone, sandy chert, and chert (fig. 141) that are oriented nearly perpendicular to the bedding. These columns range from V2 to more than 5 inches in diameter, al though they are mostly between 1 and 3 inches in di ameter ; some are several feet in length. In some areas, fragments of columns are common in the soil or talus,

but complete columns are rarely found except in cliff exposures.

Many of the sandstone columns have irregular out lines (fig. 141, A and B) ; but others, particularly those that are more cherty, tend to be plane sided, and the columns of chert are generally rather smooth sided. A few seem to branch or to have small satellitic columns on the side (fig. 14L4). Bedding planes in the host rock are interrupted by the columns, which may cross contacts betwen different rock types, but most columns occur within one host type. In a few places they cross the complete bed and are so closely spaced that they are more abundant than the host rock. The host rock may be of the same composition as the column or it may be different.

Some columns show concentric structure in cross sec tion resembling the annular rings of woody plants (fig. 141 D and F). The rings may be composed of alternat ing chert and sand or of alternating light- and dark- colored chert. The dark variety of chert is generally typical of Phosphoria types; it is microcrystalline and contains abundant spicules, grains of apatite, and sand. The light variety is chalcedonic and has flamboyant ex tinction and banding; it appears to be secondary in origin and may represent filling of shrinkage cracks. The rings seem to be restricted to cherty parts of the columns.

The sand in the sandstone columns is about the same as that in adjoining sandstone beds, but it generally contains more apatite. The apatite occurs chiefly as pellets, organic fragments and rims about quartz grains.

At Cinnabar Mountain (lot 1363) columns of phos phorite composed almost entirely of the skeletal-frag ment variety cross skeletal phosphorite beds and a bed of carbonatic mudstone. The columns average nearly 2 inches in diameter, tend to be elliptical in cross sec tion, and are separated by 1-3 inches of host rock. Overlying beds of mudstone, carbonate rock, chert, and sandstone also contain abundant columns composed chiefly of cherty sandstone and sandy chert that are as much as 4 feet in length and may constitute more than 50 percent of the total rock.

In the eastern part of the area, columns occur in al most all parts of the section. Inasmuch as the upper member of the Shedhorn Sandstone dominates the sec tion in this area, it contains the most columns; but columns are found also in the lower member of the Shedhorn, particularly in the Centennial Mountains, and also in the Retort and Tosi Tongues.

The origin of these columnar bodies is not clear. The explanation that appears to us to be most satisfactory, from the standpoint of both distribution and mor phology, is that the columns represent the burrows of


FIGURE 141. COLUMNAR CONCRETIONS OF SANDSTONE, CHERTY SANDSTONE, AND SANDY

A. Typical sandstone column showing layer structure (parallel to bedding) and irregular outline. Some cherty siltstone of transected bed(light colored) clings to column.

B. Sandstone column having unusually lobate outline, oriented as above.O. Smooth-sided column having rounded terminus. Found in float, so orientation uncertain. See D below. D. Broken end of column in C showing sandstone exterior around concentrically ringed chert center.


ENGINFFR

CHERT FROM PERMIAN ROCKS IN MADISON AND GALLATIN RANGES, MONTANA.

E. Segment of sandstone column crossing bed of laminated chert (horizontal and preserved at base). F. Cross section of column showing sandstone center surrounded by concentrically ringed chert.G. and H. Bottom (left) and top of %-inch bed of cherty mudstone containing sandstone casts of many burrows (?) and some crosscutting

columns. Many of the worm-like casts turn down at one end and cross through the bed.


bottom-dwelling animals. The fact that the columns are confined to the platform sediments indicates that any such burrowing animals were of shallow-water habitat. However, Ellis Yochelson (written commu nication, 1961), who has examined the columns in the field, stated that "they exhibit none of the characteristics that I would associate with burrows"; their origin therefore remains enigmatic.

In the Madison Range about 4 miles west-northwest of the mouth of the west Fork Gallatin River and at the top of the principal tongue of Tosi Chert Member is found a fissile to thin-bedded cherty mudstone that contains many small (^4-% inch in diameter) sand stone bodies lying in the plane of the bedding and a few larger ones iyz inches in diameter crossing the bedding (fig. 141, G and H). Xhe larger ones are like others described above, and many of the smaller ones display the same external characteristics but lie in the plane of the bedding instead of perpendicular to it. A few, however, have longitudinal ridges but are otherwise rather smoothsided. A great many of the small ones turn down at one end and cross the bedding, and others that cross the bedding have no bedding-plane counter part. These seem to be fillings of burrows made by animals that crawled through the muds and, in so do ing, passed the sediment through their digestive tracts. The relatively high content of phosphate characteristic of these bodies suggests that the phosphate may have been faecal in origin.

The upper part of the Permian sequence in the eastern part of the area the thin Retort Phosphatic Shale Member overlain by the Tosi Chert Member, which is in turn overlain by the upper member of the Shedhorn so closely resembles the sequence in the northern Teton Range of Wyoming, at Red Creek near the south boundary of Yellowstone Park, and in the Gros Ventre Range (Sheldon, 1957, pi. 13) that a direct correlation seems justified. The part of the Permian section from the base of the Retort to the Dinwoody, as formed in these parts of western Wyoming, passes westward into the upper part of the Retort Member of the Phosphoria and eastward into the Ervay Tongue of the Park City Formation (R. P. Sheldon, oral com munication, 1957) ; thus both the Tosi and the upper part of the Shedhorn of Montana are also at least partly equivalent to the upper part of the Retort of western most Wyoming and southeastern Idaho and the Ervay Tongue of central Wyoming.

AGE OF PERMIAN ROCKS IN SOUTHWESTERN MONTANA

Knowledge of the age of the Park City Formation and its correlatives in the western phosphate field and their correlation with the Permian of other areas has

been summarized by Williams (in McKelvey and others, 1956, p. 2856-2861). Fusulinids were collected from near the base of the Park City Formation at Three Forks (locality 1356) by Frenzel and Mundorff (1942), who believed them to be of Wolf camp age; Henbest con cluded that fusulinids from the same bed are middle or late Wolf camp or possibly early Leonard in age (quoted by Williams in McKelvey and others, 1956, p. 2857). Henbest (1956, p. 60) restudied fusulinids collected by Condit, Finch, and Pardee (1928, p. 192-193) at the Cabin Creek locality in the Madison Range from a horizon about 30 feet below the top of the Quadrant as defined in this paper and concluded that they are of Des Moines age. Therefore, if the lithologic correlation from Three Forks to the Madison Range is correct, the contact between the Quadrant and Park City Forma tions in the eastern part of the area must approximate the contact between the Pennsylvanian and the Per mian Systems. To the west, the Grandeur Member of the Park City includes younger beds at the top and may include older beds at the base; therefore, the lower part of the Park City near Lima and at Hawley Creek may include beds of Leonard as well as Wolfcamp age. Duncan (1961, p. B-236), reported that corals collected 66 feet and 185 feet above the base of the Park City Formation at Hawley Creek are probably pre-Kaibab in age and that these beds are therefore somewhat older than the Grandeur Member of the type area in Utah.

The Meade Peak Member of the Phosphoria and the overlying Permian strata are generally considered to be Word and possibly post-Word in age (Williams, in McKelvey and others, 1956, p. 2857), but in Montana the beds above the Grandeur Member of the Park City can be dated only by tracing them into the better known sections of Idaho, Wyoming, and Utah. Although dat ing by such a procedure compounds the uncertainties, the most reasonable conclusion is that the beds above the base of the Meade Park in Montana are also largely post-Leonard in age. How much of post-Leonard Permian time they may represent is not known.

RELATION OF PERMIAN STRATA TO OVERLYING BEDS

Jurassic beds of the Ellis Group rest disconf ormably on Permian beds in all sections along the Jefferson River and in the Three Forks and Sixteen Mile Creek areas. In the Three Forks area 50 or 60 feet of Permian beds must have been eroded away prior to Jurassic deposi tion. At all other localities examined in the area dis cussed in this report, the Permian is overlain by Lower Triassic beds.

In the Tendoy Mountains, cherty, calcareous mudstone of the uppermost Phosphoria is overlain conform-


ably by calcareous mudstone of the Dinwoody Forma tion. The Dinwoody and Phosphoria are also con formable in the western Snowcrest Range, where mudstone beds similar to those of the basal Dinwoody al ternate with chert beds having a typical Phosphoria aspect for 20 or 30 feet below the contact. In the eastern Snowcrest Range and that part of the Gravelly Range from Warm Springs Creek south, beds of the basal part of the Dinwoody rest conformably on a thin tongue of the Tosi Chert Member that contains chert, glauconite, and sand typical of the Tosi and Shedhorn but that also contains silt, clay, and carbonate typical of the basal part of the Dinwoody. Although the contact is apparently conformable at all these localities, siliceous sponge spicules, chert, glauconite grains, and apatite pellets all characteristic of the Permian beds are not present above the Dinwoody contact.

The Dinwoody Formation may rest disconformably on Permian strata in the northern Gravelly Range, for the Tosi Chert Member and the upper member of the Shedhorn have a total thickness of only 31 feet at Wig wam Creek; this evidence suggests that some beds were eroded prior to deposition of the Dinwoody Formation.

Diseonf ormity between the Dinwoody and Shedhorn Formations in the Madison Range is suggested by sev eral lines of evidence. At Shell Canyon, stringers of the basal limestone of the Dinwoody that contain coarse grains of Shedhorn-like quartzite extend downward into cracks in the uppermost bed of the Shedhorn, and at Indian Creek the thickness of the upper member of the Shedhorn changes from 64 to 80 feet within a quarter of a mile, suggesting pre-Dinwoody erosion. Further more, the uppermost beds of the Shedhorn, particularly where cherty, seem more weathered than the underlying beds in several eastern sections.

The Tosi Chert Member at Reas Peak in the Cen tennial Mountains is overlain by nearly 40 feet of sand stone of the upper member of the Shedhorn, but only 9 miles to the west a thinner section of Tosi is overlain by calcareous mudstone similar to the basal part of the Dinwoody elsewhere. An abrupt lateral change from sandstone to mudstone, particularly without an inter vening chert f acies, is unknown in this part of the sec tion in Montana; so, the upper part of the Shedhorn west of Reas Peak was probably eroded prior to deposi tion of the Dinwoody. Furthermore, the thickness of the Tosi Member varies considerably in the area where the Shedhorn is absent. A thin phosphorite bed that contains fish teeth and large abraded bone fragments at the contact between the Tosi and Dinwoody at locality 1254 also indicates a disconf ormity.

The time interval represented by the break between the Permian and Triassic rocks is not known. Kum-

mel (1954, p. 168) found lower Cythian ammonites and Claraia within 5 feet of the base of the Dinwoody, but the age of the uppermost beds of the Permian sequence is not known. Whatever the time interval represented, it certainly increases to the east, for the contact be comes more distinct in that direction, and northeast of the area, the Triassic progressively oversteps the Quad rant, Amsden, Heath, Otter, and upper part of the Madison Formations (McKee and others, 1956, pi. 2).

FACIES RELATIONS

Facies changes are implied by the iiomenclatural scheme adopted for rocks of the Park City interval and have been alluded to in the preceding discussion of stratigraphy. They are examined in more detail in the following pages.

Recognition of time horizons is, of course, essential to facies analysis. The more accurately defined and the more closely spaced the time horizons, the more sen sitive is both the delineation of environments and the analysis of their migration in time. As faunal zones have not been recognized in the Permian strata of Mon tana, time relations have been deduced from lithologic criteria, the principal one of which is the assumption that thin beds or thin distinctive sequences of beds of wide extent were deposited nearly synchronously. Ex amples are the uppermost phosphorite of the Retort Prosphatic Shale Member in the Snowcrest Range, the thin phosphorite bed in the Rex Chert Member in the Tendoy Mountains and adjacent areas, and the sequence of beds in the Meade Peak Phosphatic Shale Member in the Tendoy Mountains and the Snowcrest Range. A second criterion is presence or absence of intertonguing or intergradation, for if two adjacent lithologic units are time equivalents they should interfinger or inter- grade. In the post-Retort beds, for example, the interbedding and intergrading of chert and sandstone in many sections indicate that the Tosi Chert Member and the upper member of the Shedhorn Sandstone are equiv alent. But in the same area, the lack of interbedding of shale and phosphorite with sandstone or chert indi cates that the upper part of the Retort is not equivalent to any large part of either the Tosi or the upper part of the Shedhorn. A third and far less satisfactory lithologic criterion is relative thickness. For example, about two-thirds of the post-Retort interval at Alpine Creek consists of chert which is overlain by sandstone; but at Indian Creek, the next section to the east, the fact that chert constitutes the lower third of the interval and sandstone mostly constitutes the upper two-thirds sug gests that the chert-sandstone contact is younger toward the west.

In the following discussion, each time-rock unit is


identified by the name of the member or part of member that constitutes the bulk of the unit in the Lima region even though elsewhere the time-rock unit may be com posed partly or wholly of other members. The datum planes delineating the time-rock units are indicated on the correlation charts.

Lower Grandeur interval. We are unable to con struct a valid facies map of the lower dolomite beds of

the Grandeur Member of the Park City Formation in asmuch as the nature of the contact with the underlying Quadrant Formation is not known in sufficient detail. Nevertheless, any facies map constructed would show that rocks of early Grandeur age in most of the area west of Ruby Valley consist mainly of aphanitic dolo mite, that much of the dolomite in the Gravelly Range is granular, and that sandstone forms an increasingly

113° 111°

Rocks of Grandeur Member of Park City Formation probably eroded east of line before deposition of Meade Peak Phosphatic Shale Member of Phos- phoria Formation

EXPLANATION

(Tan) -_"^_ _ _ - (Red)

Patterns used singly in class I areas; combined in class H and II areas

FIGUEE 142. Distribution of facies in late Grandeur time. X, control point; A, control point, data approximate.


greater proportion of the interval eastward from Ruby Valley.

Upper Grandeur interval (-fig. 142). Rocks deposited in late Grandeur time consist of the upper terrigenous beds of the Grandeur Member and their probable equiva lents.

Sand is the most abundant constituent in the western part of the area at Dalys Spur and in the eastern part at Hogback Mountain. Both sand bodies grade into mud in the intervening area. Some of the mud ap parently related to the western sand area, is red, but otherwise the eastern and western terrigenous materials are indistinguishable in texture and compositions. Sandstone of this interval is more poorly sorted and more feldspathic than younger Permian sandstone. The terrigenous material passes northward, southward, and southwestward into dolomite.

Meade Peak interval (-fig. 118) . The salient features of the f acies distribution in the Meade Peak interval are the belt of high apatite content near the feather edge of the member and the area of prominent carbonate in the Lima region.

Rex interval (-fig. 143). Sand is present on both eastern and western margins in the Rex interval, but the intervening area is composed almost entirely of chert that increases in purity toward a central area in the Snowcrest Range. Mud is not sufficiently abundant to show on the f acies map, but it is more common near Lima than elsewhere. Glauconite occurs in small amounts in both chert and sandstone on the margins of the chert field; it is not present either in the class I sand areas or in the central part of the chert facies.

Franson interval (fig. 144). The distribution of sand in the Franson interval is very similar to that in the Rex interval, but in the central area the interval is made up of dolomite rather than chert, which is con spicuous only in a small area near Dillon. Skeletal carbonate rock is interbedded with aphanitic carbonate rock throughout the interval in the southwestern part of the carbonate facies; but it is not common elsewhere, and limestone makes up a significant proportion of the carbonate only in the sections west of Lima.

The Franson interval is so thick that extremes of the facies distribution are averaged out and cannot be shown in the map of the entire interval. Facies maps of two horizons within the interval illustrate two ex treme distributions. The first map (fig. 145) is of a zone in the middel of the interval, and the second (fig. 146) is of the horizon that is directly below the Retort Member in the Lima and Dillon regions. The presence

of two bodies of sand in both maps, the mud facies de rived from the west in middle Franson time, and the much greater extent of the eastern sand facies in late Franson time should be noted.

Retort interval. The lower half of the Retort Phos- phatic Shale Member of the Phosphoria pinches out to the east; so, the lithologie map, unlike that of the Meade Peak Member, is not a facies map. Unfortu nately, horizons within the member cannot be traced widely, and accurate maps cannot be constructed of intervals within the member.

Lower Tosi interval (fig. 14?)- Chert constitutes most of the lower Tosi interval. Some sand is present in the easternmost section, but the largest sand body extends fingerlike southward through the center of the area. Glauconite occurs only along the westernmost boundary between the chert and the mixed chert and sand facies. The muddy facies that enters the area from the south is, apparently, everywhere separated from the sand facies by a chert facies.

Upper Tosi interval (fig. 148) Because of difficulty in correlating an upper boundary horizon, the facies map of the upper Tosi interval has been constructed directly on the basis of field evidence rather than by calculating the D function.

A body of sand extends southward from Butte nearly to Lima, but the eastern sand extends much farther west than that in the lower Tosi interval and coalesces with the southward-extending body to form a single sheet. A muddy facies extends northward into the area, but it is less extensive than that in the lower Tosi interval.

Summary. The facies changes illustrated by the maps are listed as follows:

1. Sand to mud to carbonate.2. Sand to chert.3. Sand to chert to mud.4. Sand to carbonate.5. Sand to chert to carbonate.6. Chert and skeletal-oolitic apatite to skeletal-oolitic

apatite and mud to pelletal apatite and mud to mud to cherty mud.

7. Mud to pelletal apatite and mud to pelletal, nodular apatite and mud.

GENETIC INTERPRETATIONS

In the following discussion, the stratigraphic and lithologie data are analyzed to determine the origin of the Permian rocks in southwestern Montana. The Permian paleogeography is then reconstructed, and


13° 112° lll c

EXPLANATION

Chert Carbonate

Patterns used singly in class I areas; combined in class LI and HI areas, except that where glauconite is present the glauconite pattern is superimposed

-40-Isopeth of D vaules

Contour interval 20 units

FIGURE 143. Distribution of facies in Rex time. X , control point; A, control point, data approximate.


113° 112° 111°

359

MONTANAWYOMING

EXPLANATION

Glauconite

Glauconite pattern superimposed wherever glauconite is present; other patterns used singly in class I areas, combined in class I and Mareas

FIGURE 144. Distribution of facies in Franson time. X, control point; A, control point, data approximate.

the tectonic significance of the rock types and their facies and thickness relationships are discussed.

ORIGIN OF THE BOCK TYPES

WSJL1>SORTED SANDSTONE

LITHOLOGIC CHARACTER OF SOURCE

The small number of heavy-mineral species, the large number of tourmaline varieties, and the great predomi

nance of rounded and subrounded grains of both tour maline and zircon indicate that the sand was derived largely f ro>m older sediments. The conclusion that the sand has been reworked is not disproved by the fact that the quartz grains are angular, for Tanner (1956) stated that grains finer than about 0.1 mm do not, in general, have rounded shapes, probably because of the effect of buoyancy on abrasion. A large part of the


113° 112° 111"

45'

EXPLANATION

Patterns used singly in class I areas; combined in class II and HI areas,

FIGURE 145. Distribution of facies in middle Franson time. X, control point; A, control point, data approximate.

sand grains of the Shedhorn are therefore too fine to have been rounded, even though they may have passed through several sedimentary cycles.

The much greater abundance of chert-grains in the Shedhorn Sandstone than in sandstone of the Grandeur Member and the Quadrant Formation suggests that most of the chert grains were derived from the rework ing of the post-Grandeur Permian rocks rather than

from older rocks that may have been exposed in the source areas. Such reworking of the Permian sedi ments probably occurred near the margins of the depositional basin, where intermittent uplift of the adjoining land areas and changes in sea level would have exposed the sediments to erosion. Similarly, the apatite pellets in the Shedhorn were probably derived in large part by reworking of phosphorite, for none are present in the


113° 112° 111°

361

ONTANA WYOMING

EXPLANATION

Glauconite pattern superimposed wherever glauconite is present; other patterns used singly in class I areas, combined in class

IIand HI areas

FIGURE 146. Distribution of f acies at the end of Pranson time. X, control point showing phi median diameter of analyzed thin section;A* control point, data approximate.

Grandeur Sandstone and oolites (which might be ex pected to form if phosphate were being deposited in such an environment) are scarce.

LOCATION OF SOURCE

Facies maps of the upper Grandeur, Franson, and Bex intervals indicate that sand was derived from two

sources. A possible location of the source of the eastern sand may be inferred in part from the present distribu tion of Permian sedimentary rocks. The eastern feather edge of the Permian deposits is in the north eastern corner of the area and probably extends south eastward to near Bozeman. Permian redbeds, evaporites, and limestone are present in the Williston Basin


.3° 112° 111"

EXPLANATION

Sandstone Chert Mudstone Glauconite

Patterns used singly in class I areas; combined in class I and Hareas; where glauconite is present the glauconite pattern

is superimposed

FIGURE 147. Distribution of fades in early Tosi time. X, control point; A, control point, data approximate.

and in the northern Bighorn Basin; so, the possible location within Montana of the source area is limited to the Central Montana Platform, as defined by Sonnen- berg (1956, p. 28), and to the Sweetgrass Arch. The eastward thinning of the Permian sediments and the presence of conglomerates and pebbly beds in several of the eastern sections suggest that at least the southern

part of this source area was intermittently positive throughout much of Permian time. How much of the sand of the Shedhorn may have been derived from this area is problematical; the positive area may have ex tended into Canada, and much of the sediment may have been transported southward by longshore currents.

Facies maps of the upper Grandeur interval and


113° 112° 111"

363

Rocks of Tosi interval north of patterned area removed by pre-EMis erosion

EXPLANATION

Sandstone Cherty mudstone

FIGURE 148. Distribution of fades in late Tosi time. X, control point.

middle Franson time suggest that the western sand and the associ at ed finer detritus were derived from a source northwest of the Lima area. In the absence of strata known to be of post-Wolfcamp Permian age in central and northern Idaho and northwestern Montana, the actual location of the western source area can only be surmised; Ross (1934, p. 999) believed that the region now occupied by the Idaho batholith was positive dur ing Phosphoria time as well as during much of the rest

of the Paleozoic, and that the terrigenous material in the Permian near Dillon and Lima could well have been derived from the northern part of such a landmass. On the other hand, if the Casto Volcanics of central Idaho, which are more than 3,000 feet thick, are Permian in age as is suggested by their similarity to the Seven Devils Volcanics of westernmost Idaho that contain a Phosphoria fauna, at least part of the area of the batholith may have subsided during the Permian.


According to Scholten (1957), the area between the Lemhi Range and the Tendoy Mountains was one of recurrent uplift during the Paleozoic. The isopach and facies maps of the Permian rocks from the base of the Meade Peak Member to the top of the Retort indi cate that although the general area of the Beaverhead Range was submerged during that part of the Permian, the water in the area was shallower and the subsidence was less than in most of southwestern Montana and the range was thus a relative high. The source area may have been located northward along the trend of the relative high in the general area of the southern part of Bitterroot Range. Such a positive area and its southward extension as a submarine high might have separated the nonvolcanic southwestern Montana basin from the Casto area in central Idaho, the Seven Devils region of western Idaho, and the Baker quadrangle of eastern Oregon, where volcanics were being deposited (Ross, 1934, p. 994; Anderson, 1930, p. 13; GiUuly, 1937, p.21).

The facies maps of the lower and upper Tosi inter vals indicate that during Tosi time a considerable quan tity of sand entered the area near Butte and was trans ported southward nearly to the Idaho State line. The source areas of this sand cannot be specified. The source may have been on the west side of the basin some where northwest of the area, or the sand may have come from a northwestern extension of the eastern source.. Wherever the source may have been located, the areal distribution of this sand is much different from that of the western-derived sand of the Grandeur and Franson Members of the Park City and thus implies a different paleogeography. This implication is supported not only by the facies distribution but also by the fact that the interval from the base of the Meade Peak to the base of the Retort thins markedly from Lima to Hawlay Creek, whereas the Tosi interval does not.

ENVIRONMENT OF DEPOSITION

One of the most informative works relating grain- size distribution to environments is that of Inman and Chamberlain (1955), who studied Recent near-shore marine sediments near La Jolla, Calif., and near the Rockport, Tex., and the east Mississippi delta area of the Gulf of Mexico. Inman and Chamberlain used the fol lowing parameters in describing their data: (1) The phi median diameter, Md<f> ; (2) the phi deviation measure, <*£=% (4>84-<£l6), where <j>84 and <£l6 are the 84th and 16th percentiles, respectively; (3) the phi skewness measure, a.$=M<t> Md<t>, where M$=y± (016+084). These parameters have been calculated from the recon structed size analyses made on thin sections of several representative Permian samples; the relation between a<£ and Md(f) and between <r<£ and Md^> are plotted in

figure 149 so that they may be compared with similar diagrams by Inman and Chamberlain. With the ex ception of one sample having a relatively high positive skewness, the well-sorted sandstone field shown in figure 149 corresponds with that of the off-shore sands and near-shore shelf sands (class II) of Inman and Cham berlain.

Although turbidity currents, major ocean currents, and tidal currents all attain velocities sufficient to trans port fine sand, Eaton (1950, p. 142) stated that ordinar ily on an open seacoast only wave-induced currents have sufficient bottom velocity to set the bed material in motion. If the well-sorted Permian sand was trans ported by wave-induced currents, the inverse relation between the sorting coefficient So and the phi median diameter Md<}> (fig. 132) may be explained by reasoning similar to that employed by Humphreys (1956). As each wave passes, the horizontal current velocity varies from zero to a maximum that depends largely on the the wave characteristics and the depth of water. The sand remaining at a locality will be a lag deposit of material, brought in under very high velocities, that has a threshold velocity greater than the maximum horizontal velocity occurring during normal wave con ditions. Sand about 0.2 mm in diameter has the lowest threshold velocity (Inman, 1949). If most of the sedi ment is of fine-sand size and smaller, the grains having diameters of 0.2 mm will be removed first, and, progres sively smaller and larger grains will then move as the velocity increases. Thus the remaining sand becomes better sorted, and the mediam diameter becomes smaller through loss of the coarser fractions.

If the well-sorted sands are lag depoists, the com monly observed departure of the size distribution from log normality, as illustrated by curves 1302-Ls 44 and 1358-F 12 in figure 150, can readily be explained. For example, curve A in figure 151 represents a sand having a log normal distribution. Curve B has been derived from curve A by assuming a maximum current velocity sufficient to initiate movement of grains coarser than 0.15 mm and then by plotting the values for the dis tribution of the remaining fraction. The shape of the curve closely resembles that for the two Permian samples. The deviation of curves 1234 Us 117 and 1299-R 73 from log normality cannot entirely be ex plained in this manner, but it may have resulted from mixing of several log normal sands, possibly by bur rowing organisms.

The depth at which wave-generated currents will move sand of a given size depends mostly on the wave length and wave height which are functions of velocity, duration, and fetch of the wind. During strong gales on exposed coasts, sand might be moved at depths as


+ .5

-Tan and red mudstone

Silty sandstone

-.5

Tan and red mudstone

Silty sandstone

PHI MEDIAN DIAMETER, (Md<f>)

FIGURE 149. Relation between phi median diameter (Md<p) and sorting (<r<f>) and skewness (a<p) in Permian sandstone. Dots fromreconstructed thin-section analyses; crosses from pipette analyses.

709-931 0 63-


98

95

90

80

70

60

50

40

30

20

10

.±£L

/ /

rr7 i

DIAMETER, IN PHI

FIGURE 150. Size-distribution curves of selected samples of Permian sandstones plotted on logarithmic probability paper.

great as 200 meters, but according to Eaton (1950, p. 142), under normal conditions, the limiting depth of movement is of the order of 200 feet (about 60 meters). The class II sand in the east Mississippi delta area is, for the most part, restricted to depths of less than 60 feet (18 meters) (S'hepard, 1956, p. 2555). Similar sand in the Rockport area extends locally to depths of 50 feet (15 meters) but is found mostly above the 35- foot (11-meter) depth; at La Jolla, however, the sand extends to depths of 100 feet (30-meters).

The variables of wave height and period are, of course, not known for Permian time in southwestern Montana; so, the depth of deposition cannot be determined di rectly from the grain size. However, the facies posi tion of much of the sand shoreward from the bedded chert is strong evidence that the sand accumulated at depths of less than about 50 meters (p. 371). The ex-

treme seaward edge of the upper Shedhorn sand must have been at least 100 miles from the shore (fig. 148); so, the average gradient of the sea floor was not more than 1.6 feet per mile, much less than the average gradi ent of nearly 5.8 feet per mile of the present-day graded slope off the southern shore of Martha's Vineyard (Stet son, 1939, p. 239). Using theoretical considerations,

DIAMETER, IN PHI

FIGURE 151. Change in character of size distribution by removal of coarse fraction. Curve A, hypothetical log normal distribution. Curve B, derived from curve A by removal of values for all grains larger than 0.15 mm (2.740).

Keulegan and Kmmbein (1949) derived an equation for the stable profile of the bottom slope in a shallow sea, according to which the sea would be 9 meters (30 feet) deep. 100 miles from the shore; the average gra dient would be 0.3 foot per mile. Keulegan and Krum- bein derived the equation on the assumption that no energy was being expended transporting sediment; so,


the average gradient of the Shedhorn sea was undoubt edly somewhat greater.

The near absence of laminations, ripple marks, and crossbedding suggests that the sand was thoroughly re worked by burrowing benthonic organisms that could be expected to inhabit the sandy bottom in the inner sublittoral environment. The sandstone and chert columns are perhaps direct evidence of such a fauna.

SIGNIFICANCE OF GLAUCONITE

Glauconitic sandstone is found only near the basinward margins of the sandstone sheets. The definite facies position and the conformation of many grains to the shape of the surrounding quartz grains indicate effectively that the glauconite was in large part formed where it is now found.

According to Burst (1958, p. 315 and 318), the fac tors required for the formation of glauconite are (1) a parent material having a layered silicate lattice, (2) a plentiful supply of iron and potassium, (3) a favorable oxidation potential, and (4) a process by which the parent argillaceous material is deposited or aggregated into pelletal form. The favorable oxidation potential is one intermediate between strongly oxidizing and strongly reducing the oxygen is sufficient to oxidize all the organic matter but is insufficient to convert all the iron to the ferric state (Smulikowski, 1954, p. 96).

As emphasized by Burst (1958), the presence of glau conite indicates only the prerequisite conditions and not any specific environment. Nevertheless, surveys of glauconite occurrences show that some environments are more favorable for glauconite genesis than others, Glauconite forms generally in sea water of normal sa linity (Smulikowski, 1954, p. 95), although Shepard (1956) reported grains of glauconite-like material in distributary channels of the Mississippi delta. In modern marine deposits, glauconite occurs most com monly between depths of 10 and 400 fathoms, but in the warmer waters of Indonesia, it is found only below 30 fathoms and in abundance only below 130 fathoms (Cloud, 1955, p. 488). According to Hadding (1932), glauconite forms most, commonly in cold water or in regions where warm and cold currents meet.

Glauconite in the Permian sandstone of Montana formed in marine water of normal salinity and at depths not exceeding about 50 meters, as shown by the abun dant associated Demospongia spicules. The water was sufficiently agitated to move sand and suf ficiently aerated to support the sponges, indicating that the Eh required for glauconitization was restricted to the immediate vicinity of the pellets. The glauconite pellets do not appear to be internal casts of organisms, and they may well have been faecal pellets in which the

oxidation of organic matter would have lowered the Eh sufficiently to allow glauconitization of included clays. The distribution of the glauconite pellets may thus re flect the distribution of the pellet-producing organism.

Glauconite occurs in the Permian rocks as canal fill ings of sponge spicules as well as pellets. The favor able local environment may have resulted from the oxi dation of organic matter in the spicules, but it is difficult to imagine the infiltration of parent clay into the nar row canals. Perhaps glauconite can form from a par ent silica-alumina gel as well as from a pre-existing layered silicate lattice.

SH/TY SANDSTONE AND TAN AND RED MUDSTONE

These rock types are discussed together because they are laterally gradational and similar in both texture and composition.

LITHOLOGIC CHARACTER OF SOURCE

The character of the heavy-mineral assemblage of the silty sandstone is very similar to that of the well- sorted sandstone, and it, too, indicates that the material was largely derived from a sedimentary terrain (Weaver, 1955, p. 181). The silty sandstone and the mudstone differ in composition from the well-sorted sandstone, as they contain abundant mica shreds and clay and traces of feldspar. The presence of mica shreds and clay may indicate a, different enviroment of deposition rather than a different source, but the presence of feldspar is more difficult to explain. Its presence in silty sandstone derived from two different source areas, both of which subsequently supplied the nonfeldspathic well-sorted sand, suggests that its absence in the well-sorted sand resulted either from more severe weathering at the source during Shedhorn time or from mechanical sorting during transportation and at the site of deposition, rather than from any differences in the source rocks.

LOCATION OF SOURCE

The f acies distribution (fig. 142) clearly indicates that the silty sandstone and the tan mudstone were de rived from the same two source areas as the well-sorted sandstone. The red mudstone was derived from the northwestern source.


The parameters of size distribution of the tan and red mudstone (fig. 149) resemble most closely those of the delta silt type Ila of Inman and Chamberlain (1955, p. 122, 124), which is found in shallow distribu taries and marshes of the Mississippi delta. This seems an unlikely environment for the Permian sediments. The good sorting of the red and tan mudstone may result in part from incomplete disaggregation, and


the actual sorting may be somewhat poorer. If so, the samples would more closely resemble the "muds" of Inman and Chamberlain. These sediments border the near-shore sands in the Rockport area, but in the east Mississippi delta are found along the delta front. The silty sandstone seems most closely related to the tran sition sand class Ilia of the La Jolla area, which occurs just seaward of the type II sand. Fine material settles out because of reduced wave intensity, and sand is added to the deposit by gravity movement down the slope; the transition sand occurs only where bottom slopes are greater than 1:15 (Inman and Chamberlain, 1955, p. 114). However, in the absence of other evi dence of steep slopes, such as slumping, a gradient of 1:15 seems too great to postulate for the Permian sea floor.

The size distribution curves for two mudstones, two silty sandstones, and one well-sorted sandstone are plotted on logarithmic probability paper in figure 152.

The curves for the two mudstones and for the finer grained silty sandstone may be interpreted as indicat ing that the rocks formed from the simultaneous deposi tion of a traction load and of a suspended load, both of which had a log normal distribution (Groot, 1955, p. 95). Nearly all the coarser grained silty sandstone probably represents a traction load. Although the coarse end of the curve is irregular, it does not exhibit the marked convexity typical of well-sorted sandstone; this fact indicates that the rock had not been subjected to reworking after deposition. The lamination com monly present in both the silty sandstone and the mudstone also indicates the absence of effective wave-gen erated currents at the depositional interface.

Both the silty sandstone and the tan and red mudstone were deposited in water below effective wave base. No evidence is available to indicate the origin of the color of the red mudstone. Probably, however, the red color originated in the source area by weathering or by the

20

10

5 6DIAMETER, IN PH|

FIGURE 152. Size distribution curves of sandstone and mudstone samples of the Grandeur Member of the Park City Formation plotted on logarithmic probability paper. Curves for 1224-G-41 and 1224-G-50 from pipette analyses; others from corrected thin-section analyses.


reworking of pre-existing red beds and was preserved where the Eh was insufficient to reduce the ferric iron.

CHERT

SOURCE OF SILICA

The immediate source of most of the silica in the chert was siliceous sponge spicules. Spicules that can be observed or whose presence may reasonably be inferred by the presence of canal fillings comprise at least half and perhaps as much as two-thirds of the silica in the chert of the Phosphoria. The problem is thereby nar rowed to determining the source of the remaining one- third to one-half of the silica that is present as cement in spicular chert and in chert in which no spicules can be seen. The marked enlargement of the axial canals of nearly all spicules in chert of the Phosphoria, part of which apparently took place before final burial (p. 316), indicates that the Permian sea was undersaturated with respect to opaline silica; therefore, the matrix silica could not have been precipitated directly from sea water.

Bien and others (1958) found that much of the dis solved silica in Mississippi River water is precipitated by inorganic processes when the river water mixes with water of the Gulf of Mexico; precipitation occurs largely by adsorption of soluble silica on suspended matter as the silica comes in contact with electrolytes of the gulf water. Silica precipitated in such a manner might be available for redistribution during diagenesis, but most would be concentrated in a deltaic or esturine environment rather than in one of normal marine sa linity, which characterized the Phosphoria sea. Inas much as inorganic precipitation either directly by supersaturation or by adsorption seems unlikely to have oc curred in the Phosphoria sea, the matrix silica was probably originally incorporated in the sediment in the form of siliceous skeletal remains. The remains may have been microscleres and small megacleres of sponges, now conspicuously absent in the chert (M. W. de Lau- benfels, oral communication, 1957), or the delicate sili ceous remains of planktonic organisms such as diatoms, silicoflagellates, and radiolaria.

Although the immediate source of nearly all the silica was thus probably siliceous organisms, the nature of the ultimate source is not known. The common association of deposits of siliceous organisms with volcanic ash has led some authors to suggest that much of the silica utilized by the organisms may have been released by weathering of volcanic ash (Taliaferro, 1933, p. 54; Bramlette, 1946, p. 41). There is no evidence in the Permian rocks of Montana of more than a trace of vol canic ash from which silica could have been extracted, but Permian volcanics are common and extensive in

northern California, Oregon, Washington, and western Idaho and Nevada, and silica derived from these vol canics may have enriched the waters from which the chert was deposited. However, the calculations dis cussed in the following paragraphs indicate that normal sea water itself could have been an adequate source, and so extraordinary enrichment need be postulated.

The efficacy of sponges in extracting silica from sea water is not known, but the ability to planktonic orga nisms to extract it can be estimated from (1) the rate of accumulation of biogenic silica in pelagic sediments, (2) the rate of depletion of silica in sea water in areas of high organic productivity, and (3) the rate of pro duction of organic matter measured in areas of high productivity.

Arrhenius (1952, p. 31) found the maximum rate of accumulation of biogenic silica in sediment cores from the east Pacific to have been 860 milligrams per square centimeter per 1,000 years. The maximum thickness of bedded chert in the Phosphoria of Montana is about 200 feet (60 meters) (see figure 153). Assuming the chert to contain an average of 70 percent by volume of nondetrital quartz having a density of 2.65, a column 1 centi meter square and 60 meters high contains 1.113 XlO4 grams of nondetrital silica. At the maximum rate of accumulation of biogenic silica determined by Arrhenius in the east Pacific, 13 million years would have been required to deposit the silica in the thickest sections of the chert of the Phosphoria. This is about 30 percent of Permian time (Holmes, 1960). Present knowledge of the age of the Phosphoria Formation and its equiva lents indicates that this much time may have been avail able for deposition of the chert members.

The rate of depletion of silica in sea water in an area of upwelling can be estimated from oceanographic data. In the north equatorial divergence in the Pacific Ocean, the average silicate-silicon content of the upwelling water below the zone of photosynthesis is about 15 microgram atoms per liter; surface water moving away from the divergence contains less than 5 microgram atoms of silicate-silicon per liter (Sverdrup and others, 1942, p. 710), more than 10 microgram atoms per liter having been extracted by planktonic organisms. If 10 microgram atoms of silicate-silicon per liter (0.6 part per million SiO2 ) is the amount of depletion and if the rate of upwelling is 20 meters a month 240 meters a year (the rate of upwelling in the California current; Sverdrup and others, 1942, p. 725) the amount of silica extracted annually for each square meter of sur face is:

(240) (10s ) (0.6 XlO-8 ) =144 grams per year.

Sverdrup's data (1938) suggest that upwelling in the California current occurs across a zone about 40 kilo-


113° 112° lll c

FIGURE 153. Isopach map of combined Rex and Tosi Chert Members of Phosphoria Formation. Dashed line encloses area for which volumecalculations are made ; X, control point showing measured thickness in feet.

meters wide. If a current of this character had flowed south-southeastward across the area delineated by the dashed line in figure 153, a distance of 134 kilometers, the amount of silica extracted from the sea water yearly would have been:

144X (40X10?) (134X103 ) XlO-6=7.7XHf metric tons.

The volume of chert in the area enclosed by the dashed line in figure 153 is 6.0 X1011 cubic meters. If the chert contains 70 percent by volume of nondetrital quartz having a density of 2.65, the chert weighs:

(6.0X1011 ) X 0.7 X2.65=10.8X1011 metric tons.

It would have taken (10.8X1011)/(7.7X105 ) =1.4X106 years for the chert to have been formed by a current

of the character postulated. This period is well within the limit of time available. Silica would undoubtely be extracted elsewhere than in the zone of up welling; so, the time required would be even less. If the belt of upwelling were wider, the time required would be reduced correspondingly.

The third method of estimating the organic produc tion of silica is to calculate the amount of silica ex tracted from the measured rates of production of or ganic carbon in the modern sea. The annual production of organic carbon on the continental shelf off New York is 160 grams per square meter per year (Ryther and Yentsch, 1958). At that rate, 4.38 X106 metric tons of organic carbon would have been produced annually


in the 27,400 square kilometers outlined by the dashed line in figure 153. Fedosov (1959) listed the relative content of the principal biogenic elements in marine phytoplankton as N, 5.5-10; P, 0.14-0.5; Si, 1-22. Red- field (1958) gave 1:106 as the ratio of phosphorus to carbon in plankton. Given the median values for sili con and phosphorus in Fedosov's table, the annual pro duction of silicon in the area outlined in figure 153 would have been:

4.38X10"X11.5=1.5X106 metric tons. 106 0.32

This amount is equivalent to 3.2 XlO6 metric tons of SiO2 . At this rate of production, it would take only (10.8XlO11 )/(3.2XlO6 ) =340,000 years to extract the amount of silica in the Permian chert. The time re quired would be less if higher rates of organic produc tivity are assumed. For example, Riley and others (1949, p. 114) found the production of organic carbon in the Florida Straits to be 1.3 grams per square meter per day, or 475 grams per square meter per year. At this rate, only 115,000 years would be required to ex tract the silica in the chert of the Phosphoria.

In summary, although the time required by the first method of calculation is near the maximum amount of time available and although the second and third methods ignore solution and recycling of silica extracted by organisms, all three methods indicate that orga nisms could extract sufficient silica from normal sea water to form the bedded chert of the Phosphoria.

Silica, like other nutrients, is rapidly depleted in the zone of photosynthesis, and a continual renewal of silica in the surface waters is necessary to support to a dense population over any considerable length of time. This renewal may be accomplished by (1) the up welling of water from beneath the zone of photosynthesis, (2) the mixing of waters by turbulence where currents flow over shoal areas, and (3) the supplying of nutrients by river waters (Prokopovich, 1952, p. 878). The facies realtions of the Permian rocks do not indicate the in flux of any major system of land drainage; so, the silica may have been renewed by deeper water rising along the shelf or by turbulence in a current flowing parallel to the coast.


Most of the information in the following paragraph was supplied by M. W. de Laubenfels (oral communica tion, 1957), who kindly examined several thin sections of the chert.

The assemblage of spicules in the chert of the Phos phoria is typical of that produced by the class Demo- spongia. These sponges are shallow-water forms that do not thrive below the photic layer (approximately the

upper 50 meters, although it varies with latitude and water turbidity; see Holmes, 1957, p. 123). Demo- spongia can thrive on a rock, coarse-grained sand, or ooze substrate but not in large numbers on a fine-grained sand bottom, for the fine-grained sand particles clog the oscules. Both stagnant water and rapid currents are unfavorable; the optimum current velocity is probably about 2 or 3 kilometers an hour. A few genera live in brakish water, but de Laubenfels believed that the sponge fauna of the Phosphoria required full oceanic salinity.

The large and uniform size of the Phosphoria spicules as compared with those in modern Demospongia as semblages suggested to de Laubenfels that the spicules had been sorted. The apparent sorting of the spicules had been previously noted, and it had been suggested that the facies relations between sandstone and chert resulted in part from winnowing of spicules from the sand and their subsequent accumulation on the basinward side of the sand (Cressman, 1955, p. 26). How ever, the inability of Demospongia to thrive on a fine sand substrate indicates that no large proportion of the spicules could have originated in the area of the sand facies; the rather abrupt facies change from sandstone to chert resulted more from environmental requirements of the sponges than from sorting. Al though smaller spicules may have been transported basinward, thus extending the chert facies into deeper water, the conditions indicated by the ecological require ments of the Demospongia must have prevailed through out at least the landward portions of the chert facies; that is, the water was less than 50 meters deep and of normal marine salinity, and the current velocity was moderate.

DIAGENESIS

The principal diagenetic changes within the siliceous sediments were solution of spicules and enlargement of axial canals, cementation by silica, and alteration of opal to quartz and chalcedony.

After sedimentation, the silica content of the inter stitial water may be expected to increase and, if the sediment contains sufficient amounts of opaline silica, to eventually reach saturation. This process is illus trated by Emery and Rittenberg's core 5 (1952, p. 746) from the Santa Cruz Basin, where the silica concentra tion increases to nearly 70 parts per million approxi mately the solubility of amorphous silica at the prevail ing temperature of 4°C (Krauskopf, 1956, p. 23) at a depth of 190 centimeters below the sediment surface. The process is also substantiated by the observations of Arrhenius (1952, p. 88) and Revelle (1953, p. 34), who found that siliceous tests in pelagic sediments of the Pacific had been corroded or removed after burial.


Tests of planktonic organisms and of small and delicate microscleres would probably be dissolved first, as sug gested by the survival of spicules in the more altered rocks of the Monterey Formation (Bramlette, 1946, p. 48). The amount of silica that must be dissolved from an opaline sediment to raise the silica content of the interstitial water to saturation with respect to amor phous silica is negligible. If the original sediment con sists of 70 percent of sponge spicules having a density of 2.02 (the density of opal with a water content of 8 per cent) and 30 percent quartz and if the porosity is 80 percent, only 6.4 X 10~5 grams of silica per cubic centi meter need be dissolved to raise the silica content of the interstitial water from 0 to 80 parts per million. This amount is only about 0.025 percent of the spicular silica. Therefore, large amounts of silica can be dissolved from an opaline sediment only if there is large-scale circula tion of undersaturated interstitial water or if there is simultaneous precipitation.

The mechanism by which silica was precipitated from the saturated interstitial water is not known, but several possibilities can be suggested. First, as proposed by Arrhenius (1952, p. 85) to account for silica-cemented laminae in sediments of the East Pacific Ridge, silica might have been deposited from rising interstitial water heated at depth. In the Permian sediments, however, there was apparently no way for the entrapped water to have been significantly heated. Second, according to Baas Becking and others (1960, p. 276), the pH of connate water in strongly reducing sediments might be raised well above 9 by reduction of sulfate and preci pitation of the calcium, magnesium, and carbonate or bicarbonate. The solubility of amorphous silica in creases rapidly as the pH rises above 9 but is little af fected by pH changes below 9 (Krauskopf, 1956, p. 23). Interstitial water having a high pH and a high silica content might have evolved in the mudstone facies. Silica might have then been precipitated as the water moved either up the dip or section into the less alkaline environment of the spicule ooze.

In both cementing mechanisms suggested above, the matrix silica would have been derived largely from outside the chert facies. An alternative mechanism is that the cementing silica was derived from within the chert facies itself by simultaneous solution and deposi tion of opal, as proposed by Bramlette (1946, p. 52) for the Monterey Formation. At least three mech anisms can be suggested. First, differences in solu bility between the spicular opal and the precipitated opal might have resulted from differences in particle size. Acording to Her (1955, p. 11), the solubility of amorphous silica decreases with decreasing grain size below 50 millimicrons but does not change appreciably

above 50 millimicrons. The efficacy of such a process cannot be evaluated until the primary particle size in sponge spicules and opaline cement is determined. Second, Weyl (1953, p. 156) has observed that the solubility of silica is decreased by the chemisorption of polarizable foreign molecules, dipoles, or charged particles. The solubility of the cementing opal might have been less than that of the spicular opal because of such chemisorption. Third, the opal cement might have been precipitated as one of the polymorphs of cristobalite or tridymite that would be less soluble than the amorphous silica of the spicules. This process is suggested by the work of Swineford and Franks (1959), who found that massive opal, opal cement, and opalized wood in the Ogallala Formation (Pliocene) of Kansas gave X-ray patterns interpreted as those of low cristobalite-tridymite, whereas diatomite in the same formation was composed of amorphous opal.

Much of, and perhaps all, the chert was cemented during Permian time, as indicated by the large number of chert grains throughout the Shedhorn Sandstone and by the occurrence of chert pebbles of Phosphoria aspect in conglomeratic beds of Phosphoria age.

The siliceous spicules were originally opal, and by analogy with more recent sediments, so was the siliceous cement; but the chert is now composed of microcrystalline quartz and minor amounts of chalcedony. In general, spicules are not observed in areas composed largely of chalcedony; so, the preservation of the bioclastic texture in most areas of microcrystalline quartz suggests that the original opal was transformed di rectly to quartz without passing through an intermedi ate chalcedony stage. In opaline chert of the Mon terey Formation, chalcedony occurs generally as vein fillings or fills the large pore spaces such as chambers of Forarninifera (Bramlette, 1946, p. 18). Occur rences of chalcedony in the chert of the Phosphoria may be analogous; chalcedony veins are common, and chalcedonic spicules might be casts of spicules rather than composed of the original spicular silica. If com parison with the Monterey is valid, much of the chalce dony crystallized relatively early and probably direct ly from solution, whereas the microcrystalline quartz formed later from previously deposited opal. It should be noted, although, that under some conditions opal can be converted directly into chalcedony (White, and others, 1956, p. 54)

The undulant bedding surfaces characteristic of much of the chert are very likely a diagenetic feature, for they do not resemble any known primary structure. Although the formation of the undulant bedding can not be explained in detail, it probably resulted from the solution, migration, and redeposition of the silica;


the character of the bedding depended, at least in part, on the original permeability of the bed. The bedding surfaces of the argillaceous chert may have remained planar because the clay content reduced permeability; in contrast, the undulantly bedded chert contains less clay and was probably originally more permeable, en abling silica in solution to migrate greater distances before precipitation.

DARK MUDSTONB

SOURCE OF DETRITUS

Cressman (1955, p. 23-25) expressed the opinion that most of the silt and clay was derived from the north westerly source area. This conclusion was based part ly on the observation that post-Meade Peak sandstone derived from the east does not grade directly into mudstone whereas sandstone derived from the north west does and partly on the much greater thickness of argillaceous rocks in the Paleozoic section of Idaho than in that of central Montana. However, the f acies relations of the upper terrigenous beds of the Grandeur Member of the Park City Formation (fig. 142) indicate that fine detritus was supplied from both areas during at least part of Permian time.

SOURCE OF CARBONACEOUS MATTER

The source of carbonaceous matter in most marine sediments is marine phytoplankton (Trask, 1939, p. 436-437), and considering the wide extent of carbo naceous beds in the Phosphoria, no other source seems possible.

Rooney (1956) published 10 analyses of the C12/C13 ratio of organic carbon from the Phosphoria of Mon tana; the value of the ratio ranges from 89.90 to 91.26, and six values fall between 91.02 and 91.26. By com paring these values with those for Recent plants pub lished by Wickman (1952, p, 252), Rooney concluded that the carbonaceous matter of the Phosphoria was most probably derived from plants that grew in stag nant Water, as the value of the ratio in the Phosphoria samples was considerably higher than that in present- day marine plants. (The stagnant-water plants ana lyzed by Wickman are lacustrine types.) However, Craig (1953) found that in most sedimentary rocks, even in those containing marine fossils, the OyG1'3 ratio is about the same as in terrestrial plants. Furthermore, although C12/C13 ratio in most petroleum is higher than in the Phosphoria, most of the values for Phosphoria specimens are within the lower limit of petroleum values (Rankama, 1954, p. 198). Rooney's data, although from widely scattered local ities and different stratigraphic levels, suggest a south easterly increase in the C12/C13 ratio. Rooney inter

preted the trend as reflecting a southeasterly increase in the stagnancy of the Phosphoria sea ; however, the carbon isotope ratio is determined not only by the original isotopic composition of the carbonaceous matter but also by diagenetic and metamorphic proc esses (Forsman and Hunt, 1958, p. 773). In the ab sence of more detailed studies of the composition of the carbonaceous matter, Rooney's data can be inter preted as indicating only that the isotopic composition of organic carbon in the Phosphoria Formation is simi lar to that of organic carbon in other marine formations.

RATE OF PRODUCTION OF CARBONACEOUS MATTER

The amount of carbonaceous matter in the Retort Member within the area of 20,300 square kilometers denned by the dashed line in figure 154 has been deter mined from an isopach map of the total carbonaceous matter to be 2.03 X106 metric tons. An approximate minimum length of time required to produce this much carbonaceous matter may be calculated by assuming that the entire area was one of high organic produc tivity. If 475 grams of carbon were produced for each square meter of surface area, a rate that has been meas ured in the highly productive waters of the Florida straits (Riley and others, 1949, p. 114), the amout of carbon produced yearly in the area outlined by the dashed line in figure 154 would have been 9.64X106 metric tons. According to Emery and Rittenberg (1952, p. 776), less than a sixteenth of the carbonaceous matter produced off the coast of southern California reaches the bottom; and according to Trask (1939, p. 441), the organic content is reduced an additional 40 percent during burial and lithification. Given these values and Trask's factor (1939, p. 30) of 1.8 for the conversion of carbon to carbonaceous matter (interme diate between the ratios in plankton and in sedimentary rock), the amount of carbonaceous matter finally incor porated in the rock would be

9.64X106 ) (1.8) (0.60) ^ '\ a /v - = 6.50 X 10 lo

L . L metric tons.

At this rate, only (2.03 X1010 )/(6.50X105 ) =31,200 years would be required to deposit the amount of car bonaceous matter in the Retort Member.

The water over the entire area was probably not as highly productive as assumed in the foregoing calcula tion. A more reasonable estimate of the time required to deposit the carbonaceous matter may be made by assuming that an upwelling current similar to that off the coast of California flowed southward through the area. ( Evidence that such a current existed in Permian time is discussed on pages 379-380). Sverdrup and others (1942, p. 938) estimated the annual production of organic carbon in the area of upwelling off the coast


of southern California to be 215-430 grams per square meter. Given an intermediate value of 320 grams car bon per square meter per year and an upwelling that occurred across a belt 40 kilometers wide (p. 369), the amount of organic carbon produced yearly by the cur rent flowing a distance of 134 kilometers south-south eastward across the area enclosed by the dashed line in figure 154 would have been 1.72 X106 metric tons. The amount of carbonaceous matter finally incorporated in the rock would have been

(1.72X108 )( 1.8) (0.60) 11aw1A5 . . . - - -=1.16Xl05 metric tons per year.

At this rate, (2.03X1010 )/(1.16X105 ) =175,000 years would have been required to produce the amount of carbonaceous matter incorporated in the rock.


Under conditions of slow deposition, carbonaceous mudstone such as that in the shale member of the Phos- phoria could accumulate and be preserved only below wave base in water containing little or no oxygen. Such conditions can exist on an open shelf having no topo graphic barrier to circulation if the supply of carbo naceous matter is great and the waters impinging on the bottom are oxygen deficient (Richards and Redfield, 1954, p. 281). For example, shelf sediments off the coast of Angola and Southwest Africa are highly or ganic; upwelling supports luxuriant plankton growth, and a large part of the carbonaceous matter that reaches the sea floor is preserved because the bottom water is drawn from the oxygen-minimum layer of the open At lantic (Currie, 1953). The presence or absence of bar riers to bottom circulation must therefore be deduced from other evidence. Similarly, the presence of carbon- naceous matter and the formation of pyrite is not cer tain evidence that the bottom water contained H2S and had a negative redox potential. For example, Emery and Rittenberg (1952, p. 738, 781) found that surface sediments in basins off the California coast contain as much as 11 percent carbonaceous matter, even though the Eh of the bottom water is positive; their cores show that negative Eh values and pyrite apparently form during diagenesis. Even so, highly carbonaceous sedi ments most commonly accumulate where bottom circu lation is impeded, and in some such areas, reducing conditions prevail in the bottom waters.

PHOSPHATIC MUDSTONE

Phosphatic mudstone, though a modal type, differs from weakly phosphatic mudstone only by having a much higher phosphate content and, if the data from Sheep Creek may be extrapolated to other areas, by having a slightly greater ratio of clay minerals to quartz. The origin of the detrital and carbonaceous

fractions was probably much the same as for those of the mudstone; so, only the origin of the apatite is discussed.

SOLUBILITY OF APATITE

The most pertinent data on the solubility of apatite are those of Kazakov (1950), who studied phase rela tions at room temperature in the system P2O5-CaO-F- H2O. In his experiments that were conducted in the pH range found in the oceans, the CaO concentrations were well below that of sea water; so, his solubility data cannot be applied directly to natural conditions. The general relationships however, are informative. Very generally, Kazakov found that in acid or near neutral solutions Ca3P2O8 'H2O is precipitated, but in those having a pH more than about 7.1, the apatite Ca5 (PO4 )s (F,OH) is the stable phase. The solubility of the apatite increases slowly as the pH decreases from 10.5 to about 7.9 and then increases rapidly as the pH de creases further.

SOURCE OF PHOSPHORUS

It has generally been accepted that marine waters were the source of phosphorus in the Phosphoria. Mc- Kelvey and others (1953, p. 56-57) calculated that the Phosphoria Formation in all the western field contains 1.7 X1012 metric tons of P2O5, which is more than five times the amount in the ocean, and that over a period of 15 million years, about half of Permian time, between 15X1012 and 68X1012 metric tons of P2O5 would be added to the sea. They conclude that the ocean would have been an adequate source for phosphate of the Phos phoria but that oceanic circulation through the area would have been necessary.

MANNER OF DEPOSITION

Various hypotheses on the origin of marine phospho rites have been summarized by Mansfield (1927, p. 362) and by Kazakov (1937, p. 95). In general, the hypo theses may be divided into two groups the chemogenic and the biogenic.

The most comprehensive and persuasive hypothesis of the chemogenic origin of marine phosphorites has been advanced by Kazakov (1937). Briefly, Kazakov be lieved that phosphate is precipitated where deep waters of the sea basins, rich in phosphorus, ascend a shelving bottom. Precipitation results from decreasing partial pressure of CO2, and thus increasing pH, as the water rises. Kazakov stated that precipitation cannot occur either in the zone of photosynthesis, where phosphorus is extracted by organisms, or in the deep regions of the sea, where the CO2 content is too great; the most favor able depth is stated to be between 50 and 200 meters. The necessary conditions for precipitation are a direct connection of the zone of precipitation with the part of the ocean that lies from 200 to 500 meters below the

STRATIGRAPHY AND PETROLOGY, PERMIAN ROCKS OF SOUTHWESTERN MONTANA 375surface and the existence of cold phosphate-rich, bottom currents that ascend the shelf into,the zone of pre cipitation. A more detailed summary of the work of Kazakov and a discussion of its application to the Phosphoria Formation is found in a paper by McKelvey and others (1953). Van Vloten (1954, p. 140) pointed out that, contrary to the assumptions of Kazakov, upwelling currents are not warmed very much below the photic zone, and oceanographic data (Sverdrup and others, 1942, fig. 198) indicate that below the photic zone, temperatures, salinity, and oxygen content all remain relatively constant in the up welling mass. As discussed on page 377, oolitic phosphorite resulted directly from precipitation of apatite from sea water, but these beds, formed at depths of less than 60 meters, contain only a small amount of the total apatite in the Phosphoria.

The biogenic hypotheses postulate that the phos phorus is extracted from sea water by organisms. After death of the organisms, the phosphorus then dis solves and is then precipitated inorganically. A vari ant on the hypothesis proposed by Breger (1911) is that the phosphorus is extracted from sea water by microorganisms and deposited directly as the phosphate mineral.

The adequacy of the hypothesis indicating extraction by planktonic organisms may be tested by computing the amount of time necessary for organisms in an area of high organic productivity to extract an amount of phosphorus equivalent to that in the Retort Member. If 475 grams of organic carbon were produced each year for each square meter of area, 9.64 X106 metric tons of carbon would be produced yearly in an area equivalent to that outlined by the dashed line in figure 154. If 1:106 is the ratio of phosphorus to carbon in plankton (Redfield, 1958), 9.1 X104 metric tons of organic phosphorus would be produced. This amount should be reduced by one-fourth, or to 6.8 X104 metric tons, to account for recycling within the photic zone (Sverdrup and others, 1942, p. 40). The Retort Mem ber shown within the dashed line in figure 154 contains 9.4 X1010 metric tons of apatite, or 1.6 XlO10 metric tons of phosphorus. At the assumed rate of organic production, (1.6X1010 )/(6.8X104 )=235,000 years would be required for the plankton to extract the amount of phosphorus in the Retort. If the more reasonable assumption is made that high organic pro ductivity was restricted to a zone of upwelling similar to that off the coast of California (p. 369), the time required to extract the phosphorus in the Retort would have been 1,300,000 years.

In the ocean, inorganic phosphorus is rapidly liber ated from sinking, decaying plankton (Barnes, 1957, p.

304), and most of the phosphorus is apparently released within the upper few hundred meters of the water column (ZoBell, C. E., 1946, p. 167-169). Therefore, in order for any large amount of the phosphorus ex tracted by the plankton to have been incorporated in sediment, it seems necessary to assume that most of the Phosphoria sea below the zone of photosynthesis was saturated with phosphorus. The release of phos phorus from decaying plankton would thus have re sulted in supersaturation and precipitation.

With our present knowledge, we are not able to determine whether most of the apatite pellets resulted from biogenic or strictly chemogenic processes. More information is needed on the character of marine water in areas of upwelling and in other highly productive areas before it can be known whether any large amount of apatite can be precipitated by rising waters below the zone of photosynthesis or whether any conditions exist under which a large proportion of phosphorus ex tracted by planktonic organisms can be incorporated into the bottom sediment.

ORIGIN OF PELLETS

The pellets in the phosphatic mudstone do not appear to have been transported but were probably formed either at the surface of or within the unconsolidated sediment. Neither do they appear to have resulted from replacement of calcite pellets or oolites; for not only have we seen no evidence of any such replacement features, but we do not know of any calcareous sedi ment that even remotely resembles the phosphatic mudstone in texture.

The phosphatic mudstone is similar in texture to mud of the Clyde Sea area that consists largely of faecal pellets (Moore, 1931, p. 337). Nearly all the phytoplankton is eaten by animals (Harvey, 1955, p. 40), but Moore found that the pellets of planktonic orga nisms are friable and break down and that most of the pellets in the sediment are those of burrowing benthonic organisms. The apatite pellets of the Phosphoria may indeed be faecal pellets that have been infiltrated by phosphate, but the fine alternate lamination of pellets and mudstone and of silt and clay that is common in many specimens indicates that the sediments were un disturbed after deposition and suggests that bottom- dwelling and burrowing organisms were not common.

As pointed out by McKelvey and others (1953, p. 61), both natural phenomena and industrial pelletizing processes demonstrate that fine-grained particles may be aggregated in many ways, and a faecal origin is not proved merely by the presence of pellets. Rather, the pellets may have formed directly by precipitation from sea water, or they may have resulted from in-


113° 112° 111°

MONTANA WYOMING

FIGURE 154. Thickness of apatite in the Retort Phosphatic Shale Member of the Phosphoria Formation. Dashed line encloses area forP&rcent apatite X bed thicknesswhich, volume calculations are made. Constructed by summing

X, control point showing calculated thickness in feet; A, control point, data approximate.&f &u bedg . Q the member at each locality.

organic accretion of phosphatic material disseminated through the freshly deposited sediment.

BIMODAL FREQUENCY DISTRIBUTION OF MUDSTONE

The occurrence of distinct mudstone and phosphatic- mudstone modes in the frequency distribution of rock types in the Ketort Member could have resulted either from a preferred rate of apatite deposition or from a preferred locus of deposition. Analysis of data from the Sheep Creek section has shown that the acid insolu ble/A12O3 ratio in phosphatic mudstone is higher than that in weakly phosphatic mudstone, which suggests that the bimodality resulted from a preferred locus of

deposition. That is, phosphatic mudstone was, in general, deposited in quiter and probably deeper water than was the weakly phosphatic mudstone.

SUMMARY

Most phosphatic mudstone was deposited in quiet water below wave base. Although the surface water was sufficiently aerated to support large quantities of plankton, the bottom water contained little or no oxygen. Apatite may have been precipitated inorgani cally by an increase in the pH of upwelling water; but much, and perhaps most, of the phosphate was probably derived from planktonic organisms that extracted it


in the euphotic zone but settled into deeper phosphorus^ saturated water after death. The pellets may be re placed or infiltrated faecal pellets or may have resulted from inorganic accretion of disseminated phosphate within or at the surface of the sediment. Phosphatic mudstone was deposited in probably less agitated water than was weakly phosphatic mudstone.

PHOSPHORITE

Much of the preceding discussion applies to those phosphorites that do not seem to have been reworked as well as to phosphatic mudstone. However, the ratio of organic carbon to phosphorus in these phosphorites is much lower than in phosphatic mudstone. Several explanations are possible: (1) the apatite may have been precipitated inorganically from the sea water; (2) phosphorus may have migrated from adjacent beds; (3) currents may have removed carbonaceous matter without disturbing either the pellets or fine clastic material; (4) the oxygen content of the bottom water may have been sufficient to oxidize most of the carbon that reached the sea floor; or (5) part of the carbonaceous matter may have been converted to hydro carbons that subsequently escaped. Whichever ex planation is correct, it need apply to only a minor amount of the total apatite, for this type of phosphorite is not abundant in Montana.

A large proportion of all phosphorites and most high-grade phosphorites have been subjected to current activity and are, to some extent, mechanical concen trates. The following discussion refers to this type.

The immediate source of the phosphorus was three fold: (1) apatite pellets were reworked from phos phatic muds; (2,') phosphatic skeletal fragments were supplied by organisms; and (3) apatite was precipi tated from sea water in layers surrounding nuclei of skeletal fragments, apatite pellets, or quartz and chert grains. That the apatite oolites common in these phosphorites resulted from direct precipitation of the phosphatic material, and not from replacement of cal careous oolites, is indicated by the fact that most nuclei are skeletal fragments and pellets that were themselves originally phosphatic.

Many phosphorite beds contain fine and medium quartz sand; so, they must have been deposited at about the same depth as were sands of the Shedhorn that is, in water less than 60 meters and probably less than 30 meters deep. On the Bahama Bank, calcareous oolites occur in areas of particularly strong tidal cur rents and on beaches where warm wave-generated cur rents wash back and forth over them; they do not begin to form until the water is sufficiently warmed

to become supersaturated with calcium carbonate (Illing, 1954, p. 43). Much of the Bahaman oolitic sand has been heaped up by currents into great sub marine ridges or "dunes" (Newell and Rigby, 1957, p. 56). The oolitic phosphorites of the Phosphoria are so similar in texture to the Bahaman oolitic sands that they, too, probably formed in extremely shallow water where they were continually moved back and forth by waves. The irregular distribution of the basal phosphorite of the Meade Peak Member in the Cen tennial Mountains and in Yellowstone National Park suggests comparison with the submarine "dunes" of the Bahamas.

Reworked pelletal phosphorites were formed prob ably in somewhat deeper water, where the current velocity was sufficient to remove the fine detritus but not necessarily strong enough to move the pellets any significant distance. Similar-appearing calcareous sand on the Bahama Bank forms by aggregation of calcareous silt where the current is sufficiently strong to remove matrix silt and to prevent the formation of multiple aggregates (Illing, 1954).

The apatite oolites have obviously formed in water that was saturated with phosphorus, and inasmuch as the water was both shallow and agitated, the pH was certainly above 7.8, probably above 8.0, and perhaps as high as 8.2 (Sverdrup and others, 1942, p. 209; Bruneau and others, 19!53, table 1). The absence of significant calcite or dolomite in the shallow-water phosphorites suggests that either the salinity or the temperature, or both, were lower than in areas of carbonate deposition of the present day. Trask (1937) showed that in positive correlation exists between salinity of surface water and the calcium-carbonate content of modern marine sediments and noted that where the surface salinities are less than 34 parts per thousand the carbonate content of the sediment is gen erally less than 5 percent. The oolitic apatite rings, therefore, were probably deposited where water saturated or nearly saturated with phosphorus but having a salinity of 34 parts per thousand or less entered a shallow area where the pH was increased by contact with the atmosphere and by biologic processes.

After burial, many of .the current-deposited phos phorite beds were cemented by clear apatite. The phosphorus in the apatite cement must have migrated a significant distance, for neither the entrapped water nor the small amount of carbonaceous matter that could survive in an agitated shallow water environment would have been an adequate source, although solution at grain contacts might have supplied small amounts.


CARBONATE BOCK

PARK CITY FORMATION

By far the greater part of the carbonate rock in the Park City Formation of Montana is dolomite. The skeletal dolomite was formed from the replacement of a calcareous sediment, but the much more common aphanitic dolomite bears no direct evidence of either primary or secondary origin; however, inasmuch as there is no clear evidence that dolomite has ever been directly precipitated in a marine environment (Fair- bridge, 1957, p. 130), we assume that the aphanitic dolomite has also resulted from replacement.

The source of the calcium carbonate in the skeletal rocks is obvious, but the aphanitic carbonate rocks may have formed either as a primary precipitate or as an, accumulation of comminuted shell debris. Whether the sediment was of organic or inorganic origin, the water must have been nearly saturated with calcium car bonate, at least in the surface layers; for unlike silica, calcium carbonate can be extracted in quantity by organisms only when the salinity is high and the water is nearly saturated (Trask, 1937, pi. 71; Sverdrup and others, 1942, p. 999). During deposition of the car bonate of the Park City Formation, the surface salinity was therefore probably greater than 34 parts per thousand.

The carbonates were deposited under a wide range of current conditions. Much of the aphanitic dolomite in the Grandeur Member of the Park City was deposited in tranquil water, which, in the absence of any physio graphic barriers, must mean depths below 30 or 40 meters. On the other hand, skeletal rocks of the Franson Member must have accumulated above wave base.

Sheldon (1963) showed that in the Permian of western Wyoming, dolomite occurs shoreward from limestone of equivalent age; the distribution of rock types in the Franson Member of Montana (fig. 103) suggests a similar relationship. These facies positions of limestone and dolomite indicate that dolomitization took place soon after deposition. The grain size of the calcite (or aragonite) lutites was preserved during the dolomitization, but the presence of sandy aphanitic dolomite indicates that aggregate structures such as pellets and fossil fragments were destroyed in some beds.

FHOSFHORIA FORMATION

Carbonate rock in the shale members of the Phos- phoria Formation is interbedded with mudstone and phosphorite that accumulated below wave base in tranquil oxygen-deficient water, which are conditions unfavorable for the growth of a benthonic fauna. The

carbonate beds must have been deposited under similar conditions; so, it seems unlikely that they could repre sent accumulations of comminuted or altered shells of bottom-dwelling organisms. Inasmuch as pelagic Fo- raminifera did not exist until the late Mesozoic, the Phosphoria carbonate was probably precipitated inorganically.

The paucity of rocks intermediate in composition between carbonate rock and mudstone or between car bonate rock and phosphorite (fig. 105) indicates that carbonate was deposited much more rapidly than either the fine detritus or the apatite. This accords with the statement of Krumbein and Garrels (1952, p. 9) that when calcite and phosphorite coprecipitate because of pH increase, the ratio is very high in favor of calcite; so, the resulting sediment is composed of calcite and only a trace of phosphorite. The carbonate beds of the shale members, therefore, may have been precipi tated by a slight increase in pH, but an increase in salinity might also have resulted in precipitation.

In isolated basins in which the renewal of bottom water is slow, the deeper water tends to become sat urated with calcium carbonate (Fleming and Kevelle, 1939, p. 101). It is not surprising, then, that interbedded carbonate rock in both shale members of the Phosphoria of Montana is most commonly found in the nodular phosphorite facies which accumulated in the deepest part of the sea.

PALEOGEOGRAPHY

Permian paleogeography has been reconstructed from the distribution of facies and from conclusions on the origin of rock types and is thus more tenuous than either. Use of alternate correlations and alter nate hypotheses of origin could alter the paleogeographic maps considerably, but the reconstruction presented here is that which is best supported by the available evidence and is probably consistent and plausible.

The inferences on which the paleogeographic maps (p. 25) are based are as follows:1. Well-sorted sandstone accumulated at depths of less

than 30 meters.2. Silty sandstone accumulated below wave base on

slopes steeper than those on which well-sorted sand was deposited.

3. Chert accumulated as a spicule ooze at depths gen erally less than 50 meters.

4. Oolitic phosphorite accumulated in agitated water at depths not greater than a few tens of meters.

5. Sand was derived from a source area in central Montana and from a source area near the Bitter- root Range.


6. The land areas are assumed to have been emergent only during those times in which their presence is clearly indicated by facies distribution.

The depths of water indicated for deeper parts of the basin during deposition of the Meade Peak and Eetort Phosphatic Shale Members of the Phosphoria For mation are only rude estimates.

The evidence for the existence of two source areas has been discussed previously, but it should be empha sized that neither the configuration nor the size of either source is known and that although the general location of the source of the eastern detritus can be deduced with some confidence, only the general direc tion in which the source of the western detritus lay is known. In the following discussion the source of the western terrigenous material is termed the "western source," and that of the eastern terrigenous material, the "eastern source."

Although the rocks can be divided with little diffi culty into those deposited above and those deposited below wave base, only relative depths of accumulation can be determined within the deeper water group. For example, the nodular phosphorite facies of the Eetort Member was deposited in the deepest part of the basin, but this may have been as shallow as 100 meters or as deep as 1,000 meters. In the Pacific Ocean of the present day, the oxygen-minimum layer is at depths of 300-400 meters, and if the bottom water of the Retort and Meade Peak seas was drawn from this layer, the deeper parts of the basin must have been under at least 300 meters of water. Eichards and Vaccaro (1956) found that in the Cariaco Trench off the Venezuelan coast, anaerobic conditions are found only below depths of about 375 meters, although the maximum depth of the sill seperating the basin from the rest of the Caribbean is only 150 meters. If the bottom circulation in the Meade Peak and Eetort seas was restricted by topographic barriers, we might infer from comparison with the Cariaco Trench that the highly carbonaceous rocks of the shale mmbers were deposited under at least several hundred meters of water.

Several interesting relationships are suggested by the paleogeographic maps. Neither the eastern nor the western source supplied much sand while phosphorite and carbonaceous mudstone were being deposited, and there is no conclusive evidence that either source was emergent during most of Meade Peak and Eetort times; large amounts of bedded chert were formed when the western source supplied only small amounts of sand (Eex time) or no sand at all (Tosi time). These were the times during which the surface water was less than 34 parts per thousand in salinity but, as shown by the

sponge fauna, was still sufficiently saline to be con sidered normal marine in character. They were also times of high organic productivity. On the other hand, when the western source was supplying large quantities of sand, the salinity of the surface water was greater than 34 parts per thousand, and carbonatic sediments were deposited. Exceptions to these relationships would seem to have occurred during Early Grandeur time, but if the Grandeur Member of the Park City is equivalent to the upper part of the Wood Eiver Formation, a western land existed, but west of the area of this report.

Whenever the distribution of detritus indicates that a strong and persistent current existed, the current flowed southward and southeastward. The first evi dences of the current are seen in the upper part of the Grandeur Member of the Park City Formation. The current influenced the distribution of shallow-water sediments in both Franson and Tosi time, and it pre sumably persisted through Meade Peak and Eetort time. When the western source was supplying sand, the current apparently flowed through the extreme southwestern part of the area; but when the western source was not supplying sand, as during Tosi time, the current flowed south through the central part of the area. During such times, the salinity and probably the temperature were low. The current was thus simi lar in both direction of flow and in the character of the water to the southward-flowing California current of the present Pacific, which consists of cool (10°-15°C) subarctic water having surface salinities of 33 to 34 parts per thousand (Sverdrup and others, 1942, charts 2, 3, and 4). The Permian current, like the California current, was probably part of the major northern Pacific circulatory system.

Permian geography west of the area of this report is not well known, for the nearest rocks known to be of post-Wolfcamp Permian age are in the Seven Devils region of western Idaho, about 150 miles west of the feeaverhead Eange (Anderson, 1930). These rocks are marine volcanics. The Casto Volcanics, which occur about halfway between the Seven Devils region and the Beaverhead Eange, are somewhat similar to the Seven Devils Volcanics and may be Permian (Eoss, 1927), but neither their age nor their environment of deposi tion is known. Land areas, perhaps large ones, may have existed west of Montana, as suggested by Eoss (1934, p. 999), even during those times in which their existence is not reflected in the distribution of detritus, but the evidence of a persistent southward-flowing current of North Pacific character strongly suggests that any such land areas were insular.


At the present time, intermittent upwelling occurs in the California current at least as far north as the lati tude of southwestern Montana. The prerequisite for upwelling along a western coast in the Northern Hemi sphere is a prevailing wind having a southward com ponent parallel to the coast (Sverdrup and others, 1942, p. 501) ; the driving force for upwelling in the Cali fornia current is the northeasterly trade winds and the westerlies that in the summer actually blow over the coast from the northwest. Poole (1957) concluded from the analyses of the direction of eolian crossbedding on the Colorado plateau that during Paleozoic and early Mesozoic time the Northern Hemisphere trade-wind belt was 10° to 20° farther north than at present. If so, Montana was well within the zone of northeast trade winds.

Even though the western source may not have been subaerially exposed in Meade Peak and Retort times, the general area of the Beaverhead Range was shal lower than the basin to the east and may have served to restrict the circulation of bottom water in the south western Montana basin.

TECTONISM

During most of Paleozoic time southwestern Montana was a semistable cratonic shelf separated from the Rocky Mountain geosyncline of central Idaho by a recurrently positive hinge that migrated between the Tendoy Mountains of Montana and the Lemhi Range of Idaho (Scholten, 1957, p. 168). The relations of the Permian of southwestern Montana extend this con cept of the Paleozoic tectonic framework into Permian time.

The general area of the Beaverhead Range subsided less rapidly than did the Tendoy-Snowcrest area in Permian time, and by analogy with the earlier Paleo zoic it may be considered to be part of the hinge sepa rating the semistable cratonic shelf of southwestern Montana from a geosyncline to the west. The width of the hinge area is not known, but thick eugeosynclinal deposits were being formed in westernmost Idaho.

The area now occupied by the Snowcrest Range and the Tendoy, Blacktail, and Pioneer Mountains was sub merged throughout Permian time. Although the area was mainly one of subsidence, intermittent uplift periodically brought deeper water sediments to above wave base, resulting in the winnowing and reworking of the sediments and in the superposition of shallow- water sediments on deep-water sediments.

The area east of Ruby Valley may be considered to be part of the craton proper. The part of the area from the Gravelly Range to the Gallatin Range was sub merged most of the time, but the water was shallow

and the accumulated sediments were relatively thin. During at least part of Retort time, the area of the Madison Range appears to have subsided more than the areas of either the Gravelly or Gallatin Ranges. The Sweetgrass Arch and the Central Montana Plat form were low positive .areas much of the time, but movements of small amplitude resulted in expansion and contraction of the land area and in intermittent reworking of sediments about its margin.

The vertical movements of the three major tectonic elements the eastern source area, the southwestern Montana basin, and the northwestern source area are illustrated in figure 155. The sequence of uplift and subsidence in the Beaverhead Range was probably similar to that of the western source area, but the range was entirely below sea level. The three tectonic elements moved in concert from the beginning of Meade Peake time through Retort time, but not in Grandeur or Tosi times.

The uplift and subsidence from the beginning of Meade Peak time through Retort time when the three elements seem to have moved together may have re sulted from eustatic changes in sea level, but differential vertical movements, perhaps basement-controlled, seem to have occurred during Grandeur and Tosi times.

Both the basal bed of the Meade Peak Member and the uppermost bed of the Permian sequence are shallow- water deposits over most of the area; so, the thickness of beds from the base of the Meade Peak to the base of the Dinwoody is a close estimate of the net amount of subsidence in post-Grandeur time (fig. 156). Maxi mum net subsidence was about 500 feet in the vicinity of Lima. The Beaverhead Range subsided nearly 300 feet; half of the subsidence took place in Tosi time. Subsidence in the northern and eastern parts of the area can only be estimated because of post-Permian erosion, but it probably amounted to less than 200 feet.

TRANSGRESSION AND REGRESSION

The sequence of Permian strata in western Wyoming, which is very similar in character to that in south western Montana, was explained by Sheldon (1957, p. 152) as having resulted from two transgressions and regressions of areally zoned environments. The major features of the Permian sequence in southwestern Mon tana may be explained in a similar manner. The phosphatic shale members represent two transgressions, whereas the two members of the Shedhorn Sandstone and their equivalents represent two regressions. The record in Montana, however, is not as clear as that in Wyoming. Transgressive and regressive relationships are obscured by sand from two source areas that were


NORTHWESTERN SOURCE AREA BASIN

EASTERN SOURCE AREA

Tosi time

Retort time

Franson time

Rex time

Meade Peak time

Grandeur time

Quadrant time

HIATUS

mEXPLANATION

Subsidence

Uplift

Below sea level

FIGURE 155. Vertide movements of Permian tectonic elements.

not always rising or subsiding simultaneously, and in termittent uplift of the source areas destroyed parts of the record in the marginal parts of the basin.

SUMMARY OF PERMIAN EVENTS IN SOUTHWESTERN MONTANA

During Quadrant time, sand was spread westward across southwestern Montana. Deposition kept pace with subsidence and the sea remained shallow over the entire area, but in Early Permian time either increas ing subsidence or a decreasing supply of sand resulted in a lowering of the sea floor in the areas west of the Ruby River and in the deposition below wave base of carbonate lutite of the Grandeur Member. The car bonate facies may have transgressed eastward. In central Idaho a land area probably existed that to some extent restricted oceanic circulation in the southwestern Montana sea. The Grandeur sea was relatively warm and saline and lacked strong currents.

Toward the end of Grandeur time subsidence in the center of the basin was accompanied by a complement-

70&-931 O 63 8

ary uplift in the eastern source area located in central Montana and by uplift of a source area to the north west, perhaps near the site of the Bitterroot Range. Both sources were composed of older sediments. A Current flowed souther istward through the southwest ern corner of the area and distributed detritus from the northwestern source area. Carbonate continued to be deposited.

The record of earliest Meade Peak time is not pre served in Montana, for whatever sediments may have been deposited were removed on subsequent uplift. The first Meade Peak sediments preserved in the area were deposited in a siallow sea that in most places could not have been more than a few tens of meters deep. Neither source area supplied sand, and both may have been submerged. Water rich in phosphorus moved upward onto the shallow shelf and became su persaturated by an increase of pH that resulted from photosynthesis and from contact with the atmosphere. Apatite was then deposited in the shallow agitated wa ter as oolitic rings aroind nuclei consisting of skeletal


113° 112° 111°

Strata partly stripped by pre-Ellis (Jurassic) erosion

a partly stripped by pre-Dmwoody (Triassic) erosion

FIGURE 156. Isopach map of strata between the base of the Meade Peak Phosphatic Shale Member of the Phosphorla Formation and the base of the Dinwoody Formation. X, control point showing measured thickness in feet; A, control point, data approximate.

fragments, reworked pellets, and quartz grains. The oolites were continually washed back and forth and in places were piled up in banks. The water was cool and, although still normal marine in character, of rela tively low salinity.

The rate of subsidence increased in late Meade Peak time, and the sea floor in much of the area was lowered well below wave base. A submarine ridge near the Beaverhead Kange may have restricted bottom circu lation!. A current, probably upwelling, that flowed southward through the area and consisted of cool sub arctic marine water having relatively low salinity sup ported a rich growth of plankton. After death, the

planktonic organisms settled into deeper water, either directly or as faecal pellets of grazing zoo-plankton, and supplied both carbon and phosphorus to the bottom sediments. Water below the photic zone was deficient in oxygen and saturated with phosphorus. Water in the deepest part of the basin periodically became super saturated with calcium carbonate, which was then rapidly precipitated.

At the beginning of Hex time, the sea floor was raised to within the photic zone over most of the area, prob ably by uplift rather than by sedimentary filling. The eastern source area again supplied sand. The south ward-flowing current supported a dense Demospongia


population, and spicules accumulated to form a silice ous ooze. Currents winnowed out some of the smaller spicules and deposited them with silt and clay in those parts of the basin that were below wave base. The growth of calcareous organisms was inhibited by the low temperature and salinity of the inflowing subarctic water. The northwestern source area locally supplied some sand in Rex time.

Sand and silt were supplied by the northwestern source area during all of Franson time. Much sand was also derived from central Montana during early and late Franson times, but carbonate sediments trans gressed as far east as the Madison Eange during the middle of the interval. Emergence of the northwest ern source area deflected the major southward-flowing current west of the area, and the sea in southwestern Montana became warmer and more saline. The sea continued to be shallow, probably no deeper than 30 or 40 meters in most places, and skeletal carbonate sands were deposited. Subsidence was slow and was approx imately compensated by sedimentation.

Sharp subsidence marked the beginning of Eetort time. Neither source area supplied sand, and both may have been submerged. A submarine ridge ex tended southward approximately along the present Montana-Idaho State line. Submergence of the north western source area again permitted the southward- flowing current to move through the area. Plankton bloomed and supplied carbon and phosphorus to the bottom sediments, as in late Meade Peak time. These conditions were interrupted briefly in middle Retort time by uplift in the eastern part of the area that re sulted in the deposition of sand and chert now exposed in the Snowcrest Range and possibly in the destruction of lower Retort sediments that may have been deposited east of Ruby Valley. Events in late Retort time were similar to those in early Retort time; but the basin was not as deep, and phosphatic mud deposited in the Snow- crest and Dillon areas was intermittently reworked. Late Retort subsidence in the Madison Range resulted in the deposition of deeper water sediments there than to the west in the Gravelly Range. Some of the deeper water, rich in phosphorus, moved eastward onto the shallow shelf, where apatite was deposited as oolites by an increase in pH.

In Tosi time, most of the basin was again under less than 50 meters of water, probably largely as the result of uplift. Sand was again derived from central Mon tana, but the northwestern source area was either of small extent or remained submerged. The southward- flowing current continued to sweep through the area

and distributed sand from an unknown source as a long tongue extending southward. The area not covered, by sand supported a dense sponge population, and its floor was covered by a spicule ooze. Sand gradually spread westward from the central Montana source area and eventually filled the study area from the shore to the southward-extending tongue. Toward the end of Tosi time, the salinity increased to a concentration where some carbonate was deposited. Tosi time was probably succeeded in much of the area by a period of noiideposition that possibly resulted from base-leveling of central Montana and the attainment of a profile of equilibrium in southwestern Montana, but sedimenta tion may have continued into Triassic time in the. Lima region.

STRATIGRAPHIC SECTIONS

INTRODUCTION

The stratigraphic sections measured in southwestern Montana as part of the U.S. Geological Survey's in vestigation of the western phosphate field and the chem ical analyses of the sampled beds are presented in the following pages. Specific credit for each measured section is given in the heading for the section. The rock names assigned in the field have been revised where necessitated by the chemical analyses or by the study of hand specimens and thin sections. Swanson is re sponsible for the revision and final preparation of the stratigraphic sections in the Madison and Gallatin Ranges and the Centennial Mountains; Cressman is responsible for the others. Brief descriptions of thin sections have been added to several of the stratigraphic sections in the Madison and Gallatin Ranges where rel atively close-spaced samples have been studied.

The rock names in the bed descriptions consist of (1) a noun denoting the dominant constituent, (2) adjec tives denoting other constituents present in amounts greater than 20 percent that are arranged from left to right in order of increasing abundance, and (3) adjec tives also arranged from left to right in order of increas ing abundance that describe the size and type of grains comprising the dominant constituent. The rock name is combined with terms describing hardness, thickness of bedding, and color; additional information, such as the presence of an unusual or distinctive mineral occur ring in amounts of less than 20 percent or the grain size of a subordinate constituent, is denoted by phrases such as "contains glauconite" or "quartz sand is fine." The terms used have been defined on page 282.

The sections are arranged in order according to the lot number; so, sections in a particular area must be located by first referring to plates 14 or 15.


Shell Canyon, Mont., lot[Permian rocks measured, and Retort Phosphatic Shale Member of Phosphoria Formation sampled from cliff exposures and hand trench on north side of Shell Creek Canyon

about 600 ft above canyon floor, SEJ4NEJ4 sec. 33, T. 6 S., R. 1 E., Madison County, Mont., near crest of small denial structure at west side of Madison Range synclme, in August 1947. Beds strike about N. 5° W. and dip 10-15° W. Measured by R. W. Swanson and sampled by 3. A. Mann and 3. Q. Evans. Analyzed for PsO5 and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Qeol. Survey]

Chemical analyses (percent)

Bed

D-76.

Us-75.

74.

73.

72.

71.

70.

Description

Din woody Formation, basal bed:Limestone: dolomitic, hard, very finely

crystalline, medium- to thick-bedded, light-brownish-gray (5YR 6/1). Stringers penetrate underlying bed. Contains many Lingula shells in lower part.

Upper member of Shedhorn Sandstone:Sandstone: locally carbonatic and

cherty, very fine grained, hard, light-brownish-gray (5YR 5/1). Maximum overgrowths on dusty- rimmed subrounded quartz grains. Light-brown apatite pellets, 10 per cent, including some rims on quartz grains; chert grains, 5-10 percent. Stringers of limestone projecting from overlying bed into cracks in the quartzite contain coarse grains of similar quartzite having minor car bonate matrix, and carbonate pene trates very little beyond walls of cracks in quartzite, suggesting early silicification (overgrowths) and sub sequent unconformable deposition of limestone of the Dinwoody.

Sandstone: very fine grained, hard, thick-bedded to massive, light- brownish-gray (5YR 6/1). Small chert concretions and lenses in upper 2 ft and laminated chert common near base. Somewhat calcareous in lower part. Basal contact irregular.

Chert and sandstone: thin-bedded hard light-brownish-gray (5YR 6/1) chert mottled with dark gray and crossed by closely spaced 1- to 3-in.-diameter columns of hard very fine grained light-brownish-gray (5YR 6/1) to brownish-gray (5YR 4/1) sandstone containing small dark apatite pellets. Bed is 2 ft thicker 300 ft to east.

Sandstone: hard, thick-bedded, medium-grained (coarser near top), light-brownish-gray (5YR 6/1).

Carbonate rock and sandstone, interlaminated: cherty, sandy microcrystalline carbonate rock interlaminated with cherty, calcareous very fine grained sandstone; both are hard and light-brownish-gray (5YR 6/1). Carbonate generally more finely crystalline in carbonate- rock layers and commonly rhombic in sandy layers and in cherty areas; quartz grains subangular having common but incomplete overgrowths; chalcedonic chert is disseminated through carbonate rock and locally constitutes the principal cement of sandstone layers and irregular patches in carbonate-rock layers; chert grains and clear to dusty light- brown apatite pellets common in the sandstone. Layers thicker and car bonate content greater near top.

Sandstone: fine-grained, hard, light- brownish-gray (5YR 6/1); contains numerous apatite pellets.

Thick- Cumulativeness thickness(feet) (feet) Sample

Uranium

PaOsAcid in

solubleRadio- Chemical

metric eU U

0. 75 0. 75

6. 0 6. 75

3. 4 10. 15

12.95

1. 45 14. 4

15. 1


Shell Canyon, Mont., lot 1214 ContinuedChemical analyses (percent)

Us-69.

68.

67.

66.

65.

64.

63.

62.

61.

60.

Description

Upper member of Shedhorn Sandstone Continued

Chert and sandstone, interbedded: hard sandy grayish-brown to light- brownish-gray (WYR 4/3 to SYR 6/1) chert interbedded with fine grained light-brownish-gray cherty sandstone. Quartz grains moder ately well rounded and dusty rimmed by overgrowths; overgrowths are euhedral in contact with phosphate but are corroded in chert layers; chert grains common in sandstone, chert layers rich in sponge spicules; beds contain about 5 percent color less to brown apatite pellets and numerous phosphatic shell fragments and sponge-spicule canal fillings. Contacts between layers very sharp.

Chert: sandy, hard, grayish-brown (10 YR 4/3) to light-brownish-gray (SYR 6/1). Contains thin interbeds of fine-grained sandstone at base and irregular patches of sand elsewhere.

Sandstone: hard, fine-grained, thick- bedded to massive, light-brownish- gray (SYR 5/1). Contains chert 2.5 ft above base. Quartz grains mod erately well rounded and dusty rimmed by extensive overgrowths; in places, patches of chert contain ing indistinct sponge spicules; chert grains common in sandstone; bed contains 5 percent clear to dusty light brown apatite pellets and sponge-spicule canal fillings; rounded carbonate grains fairly common; rhombic carbonate grains in chert. Calcareous chert lenses are found along strike.

Chert: hard, thick-bedded, brownish- gray (SYR 4/1); locally sandy.

Sandstone: cherty, hard, fine-grained, thick-bedded, medium to light- brownish-gray. Chert lenses and nodules common in basal half and scattered in upper 1 ft. Irregular basal contact.

Chert and sandstone: very irregularly bedded hard light-gray (N 8) chert (75 percent) and hard fine-grained light-brownish-gray (SYR 6/1) sand stone. Irregular basal contact.

Sandstone: hard-fine-grained, thick- bedded, light-brownish-gray (SYR 5/1). Irregular basal contact.

Sandstone and chert, interbedded: thick-bedded hard very fine grained brownish-gray (5YR 4/1) quartzitic sandstone (60 percent) interbedded with hard light-gray (N 8) sandy chert (40 percent). Irregular basal contact.

Sandstone: hard, fine-grained, thick- bedded, light-brownish-gray (5 YR 6/1). Irregular basal contact.

Chert: locally sandy, hard, poorly bed ded, light-brownish-gray (SYR 6/1).

UraniumThick- Cumulativeness thickness(feet) (feet) Sample

Acid in- Radio- Chemical soluble metric ell U

2. 1 17. 2

1. 5 18. 7

3. 4 22. 1

1. 0 23. 1

3. 0 26. 1

5. 8 31. 9

2. 9 34. 8

11. 3 46. 1

5. 2 51. 3

1. 7 53. 0


Shell Canyon, Mont., lot 1214 Continued

Bed

Us-59-

58-

57-

56-

To-55-

54.

53.

52-

Description


Sandstone: hard, fine-grained, massive, brownish-gray (5YR 4/1). Quartz grains moderately rounded by much secondary growth; dusty orphosphat- ic rims on original grains very com mon; contains 5-10 percent brown and, in places, clear apatite pellets and sponge-spicule canal fillings; bed contains 5 percent carbonate grains generally rounded, some rimmed by phosphate and some by well-formed overgrowths. Irregular basal contact.

Chert: hard, thin-bedded, medium- gray (N 5) to brownish-gray (5F.R 4/1); contains about 10 percent of lenses of hard fine-grained light- brownish-gray sandstone. Irregular basal contact.

Sandstone: hard, fine-grained, thick- bedded to massive, brownish-gray (5YR 4/1). Basal contact gradational over narrow zone.

Sandstone: cherty, hard, fine-grained, not bedded, light-brownish-gray (5 YR 5/1); cherty patches irregularly dis tributed.

Tosi Chert Tongue of Phosphoria Formation:Chert: hard, thin- to thick- and rather

poorly bedded, medium-dark-gray (N 4); locally sandy; contains persistent sandstone parting at base, and in lower 1 ft, contains a few irregular lenses of hard, very fine grained to coarsely silty grayish- to dusky-brown (5YR 3/2- 2/2) sandstone; sandstone contains nearly 15 percent phosphate, and has chert cement (20 percent). Quartz mostly subangular to angular; many grains show overgrowths, some on top of phosphate rims; apa tite as clear to dusty pellets, and light- to dusky-brown sponge-spicule canal fillings and rims on quartz grains; chert grains common; some sponge spicules evident; carbonate (5 percent) chiefly as rounded grains, some with phosphate rims and over growths.

Sandstone and chert: top 0.2 ft and basal 0.1 ft composed of sandy hard black (N 2) chert; rest composed of har,d cherty fine-grained dusky-brown (5YR 2/2) sandstone; irregular con tacts between layers. Basal contact irregular.

Chert: hard, thin-bedded, brownish- black (5YR 2/1); contains very thin mudstone partings. Basal contact gradational.

Chert: hard, thin-bedded, brownish- black (5YR 2/1); thickness of beds increases upward; contains thin fissile mudstone partings. Basal contact gradational.



Acid in- Radio- Chemical soluble metric e~U U

1. 6 54. 6

3. 0

5. 3

1. 7

4. 6

57. 6

62. 9

64. 6

69. 2

69. 9 RWS-24-47 1. 6 90. 2 0. 0005

3. 2 73. 1

4. 15 77. 25

23-47

22-47

.6 86.7 .0005 __-_.__

.8 84. 7 . 0005 0. 000


Shell Canyon, Mont., lot 1214- Continued

Bed Description

Tosi Chert Tongue of Phosphoria Forma tion Continued

To-51____--_- Chert: hard, thin-bedded, dark-gray (N 3) banded in part by medium gray (N 5); contains fissile brownish- gray (5YR 4/1) mudstone partings. At 0.6 ft above base is a vuggy lenticular calcareous concretion about 0.3 ft across and 0.15 ft thick lined with calcite crystals; chert layers are warped around the con cretion and are thinner above and below central part. Basal contact gradational.

50 ________ Chert and mudstone, interbedded:hard thin-bedded gravish-blac^ (N 2) chert (80 percent) interbedded with hard fissile dusky brown (5YR 2/2) mudstone (20 percent), uon- tains vuggy concretion similar to that in bed To-51 at 0.8 ft above base and others in cliff nearby at similar horizon. Basal contact gra dational.

49__ ______ Chert and mudstone, interbedded:hard thin-bedded grayish-black (N 2) chert (75 percent) interbedded with hard fissile brownish-black (5YR 2/1) mudstone (25 percent); thin section reveals distinct lamina tion that is due chiefly to distribu tion of quartz grains, organic mat ter (?), and calcite but also that reflects the texture of chert; contain numerous sponge spicules; grains angular to moderately rounded; quarfz grains of silt to very fine sand size; carbonate tends to be rhombic. Crosscutting stylolite. Sharp basal contact.

Retort Phosphatic Shale Tongue of Phos phoria Formation:

Rt-48_-_--__- Mudstone: silty, hard, alternating fis sile to thin-bedded, brownish-black (5YR 2/1). Basal contact irregular.

47________ Phosphorite: cherty, muddy, hard,poorly bedded, grayish-ulack ( N2), coarsely oolitic, coarsely nudular in upper part; apatite partly pelletal but mostly oolitic; fossil nuclei common; pellets commonly rich in sponge spicules and dusty with carbonaceous material; chert errati cally distributed, locally comprising all cement and in places oolite nuclei ; laminated carbonate at top is prob ably algal.

46________ Mudstone: carbonatic, hard, thin- tothick-bedded, laminated in part, grayish-brown (5YR 3/2) to dark- gray (A 3); carbon micro crystalline; quartz mostly silt size and angular, larger grains rounded. Basal contact gradational.

45________ Mudstone: cherty, hard, fissile tothin-bedded, brownish-black (5YR 2/1); lower part calcareous. Basal contact gradational.

44________ Mudstone: cherty, hard, thin-bedded,locally fissile to laminated, dusky- brown (5YR 2/2).



5. 0 82. 25 RWS-21-47

Uranium

P 205Acid in

solubleRadio-

metric e~UChemical

V

0. 5 85. 0 0. 0005

5. 2 87. 45 20-47 .6 82. 1 . 0005 0.000

5. 1 92. 55 19-47 .9 82. 3 . 0005 .000

1. 2 93.75

55 94. 3

18-47

17-47

1. 1 73. 7 . 001

19. 2 43. 9 006

.000

.003

1. 15 95. 45

3. 7 99. 15

. 75 99. 9

16-47

15-47

14-47

. 9

.6

50.0

74.9

72.0

.001

.001

.0005 .000


Shell Canyon, Mont., lot 1214 Continued

Bed Description

Retort Phosphatic Shale Tongue of Phos-phoria Formation Continued

Rt-43________ Mudstone: hard, fissile to thin-bedded,dusky-brown (5YR 2/2). Thin sec tion shows strong lamination; quartz fine-silt size, elongate grains parallel to bedding, muscovite rods com mon, carbonate (15 percent) microcrystalline to cryptocrystalline.

42________ Phosphorite: cherty, friable to hard,medium- to coarsely pelletal, thick- bedded, grayish-black (A 2). Apa tite mostly pelletal, partly oolitic; many pellets contain fossils (Fora- minifera?) that comprise much of pellet; much of matrix also phosphatic; chert constitutes much of the cement and the centers and cracks of many phosphate pellets and corrodes perimeters of some pellets. Basal'contact irregular.

41__-_-__- Phosphorite: medium- to coarsely pel letal (finely pelletal at base), friable, brownish-black (5YR 2/1). Apatite fairly similar to that in bed Rt-42 except that it is not cherty and there is not much matrix between the pellets; pellets fit together closely; fossils within pellets are very numer ous; finer grained layers contain con siderable amounts of carbonaceous material.

40_ _______ Phosphorite: medium coarsely pelletal,friable to medium-hard, thin and irregularly bedded, brownish-black (5YR 2/1). Characteristics in thin section, similar to bed Rt-41, but oolites common in some layers and fossils much less abundant.

39________ Mudstone: silty, medium-hard, thin- bedded, dark-gray (N 3); contains about 25 percent angular, elongate quartz grains and 10-15 percent mica plates in a dark-brown to black matrix that includes some apatite pellets.

38________ Dolomite: silty, microcrystalline, me dium-hard, massive, brownish-gray (5YR 4/1); contains considerable amounts of fine black carbonaceous matter.

dqlomitic, soft, dusky- 2/2); unit highly

37.

36.

35.

34_

Mudstonebrown (5YRsheared.

MudstoneRt-37.

unit sheared and much like Irregular basal contact.

Mudstone and phosphorite: thin layers of phosphorite at base and top and mudstone in middle; phosphorite medium coarsely pelletal, medium- hard, grayish-black (N 2); mudstone probably carbonatic, soft, dusky- brown (5YR 2/2); mudstone and upper phosphorite sheared.

Sandstone and chert: hard dusky- brown (5YR 2/2) mudstone parting at base overlain by 0.2 ft hard brownish-black (5YR 2/1) chert and 0.8 ft hard medium-bedded fine grained weak-brown to brownish- black (5YR 3/2-2/1) phosphatic sandstone that is darker and more phosphatic upward. Irregular basal contact.



2. 05 101. 95 RWS-13-47

Uranium

Acid in- Radio- Chemical soluble metric eV U

0. 1

. 75 102. 7 12-47 23. 6

80. 5 0. 001

30. 2 . 008

0. 000

.006

. 5 103. 2 11-47 32. 4 8. 1 . Oil . 013

1. 5 104. 7

. 5 105. 2

1. 2 106. 4

. 8 107. 2

. 45 107. 65

. 65 108. 3

10-47

9-47

32. 5 8. 4 . Oil . 009

3. 7 70. 6 . 004 .001

8-47

7-47

6-47

5-47

.5 20. 0 . 0005

3. 6 55. 2 003

6. 0 47. 3 . 005 . 003

14. 9 40. 4 . 009 . 004

1. 0 109. 3 4-47 ). 5 70. 5 . 003 . 002



Bed Description

Lower member of Shedhorn Sandstone:Ls-33._______ Sandstone: hard, thick-bedded, fine

grained, light-brownish-gray to medi um-gray (5YR 5/1-AT" 5) quartzitic. Irregular basal contact.

32_ _______ Sandstone: cherty, hard, thick-bedded,fine- to medium-grained, medium- dark-gray (N 4); quartz is subangular and has minor overgrowths; chert abundant as cement; abundant sponge spicules. Basal contact ir regular.

31_-______ Sandstone: cherty, hard, medium- grained, light-brownish-gray (5 YR 5/1), quartzitic; quartz subangular to subrounded with some over growths; abundant cherty matrix contains many sponge spicules, some having overgrowths; contains scat tered apatite pellets and somewhat similar appearing but less well rounded grains of chert.

30________ Sandstone: hard, medium - grained,thick - bedded to massive, light - brownish-gray (5YR 5/1); medium- gray (N 5) at base.

29________ Chert: hard, thin- to thick-bedded,medium-dark-gray (AT 4) to grayish- black (N 2); calcareous near top; contains irregular lenses of fine brownish-gray (5YR 4/1) sandstone. Irregular basal contact.

28_ _______ Sandstone and chert: 0.3-0.4 ft bed ofsandy hard medium-gray (A 5) sand stone grading upward to brownish-gray (5YR 4/1) sandstone containing scat tered chert nodules. Quartz is mostly subangular to subrounded and has ex tensive overgrowths; about 5 percent apatite, chiefly well-rounded, clear to moderately dusty light-brown pellets; also contain shell fragments and angular coarse-grained fragments of probable apatite nodules; also con tain rounded chert, carbonate grains, and some interstitial carbonate. Irregular basal contact.

27_ _______ Dolmite: sandy, hard, thick-bedded,light-brownish-gray (5YR 6/1), fine grained; pebbles of chert, carbonate rock, quartzite, and phosphorite as much as \% in. diameter at top, mid dle, and base of bed. Pebbles of carbonate rock, generally cherty, and of spicular chert and phosphorite; quartz grains are as much as J^mm but mostly less than }4mm in dia meter and are subrounded by com mon but not very obvious over growths; apatite occurs as pellets, spicule canal fillings, and pebbles or grains of spicular nodules; carbonate in sandstone and chert is generally very fine grained, but some is coarse and probably secondary; much of carbonate in chert is rhombic.

Franson Tongue of Park City Forma tion:

F-26._______ Dolmite and sandstone: irregularlydistributed hard fine-grained thick- bedded to massive light-brownish- gray (5 YR 6/1) sandy dolomite and dolomitic sandstone.

UraniumThick- Cumulativeness thickness(feet) (feet)

1.9 111.2

85 112. 05

112. 75

Sample

RWS-3-47

2-47

Acid in- Radio- Chemical P2O 5 soluble metric ell U

1. 1 90. 1 0. 0005 0. 002

1. 0

1-47

93. 3 . 0005

92. 2 . 0005

.000

.000

5. 55 118. 30

3. 75 122. 05

2. 5 124. 55

1. 1 125. 65

2. 0 127. 65



F-25.

24.

23.

Ls-22.

F-21.

Ls-20.

F-19.

18-

17.

16.

15.

Description

Fransan Tongue of Park City Formation Continued

Dolomite: sandy, hard, fine-grained, medium-gray (N 5).

Chert: very sandy, hard, spicular, yel lowish-gray (10 YR 8/1); quartz sand is very fine; contains streaks and lenses of fine-grained pale-brown (10 YR 5/2) dolomitic sandstone.

Dolomite: sandy, hard, very fine grained, massive, light-brownish- gray (5YR 6/1). Gradational basal contact.

Sandstone: dolomitic, cherty, hard, massive, fine-grained, pale-brown (WYR 6/2) to light-gray (N 7). Thin section reveals numerous grains of dense carbonate rock as much as 5 mm long having finely crystalline carbonate in matrix; cherty zones are spicular and contain shell frag ments and pellets of apatite and rhombic abraded carbonate. Un dulating basal contact.

Dolomite: sandy, locally pebbly, hard, very fine grained, thick-bedded, pale-brown (WYR 5/2).

Sandstone and chert: hard very fine grained locally pebbly thick-bedded yellowish-gray (WYR 7/1) sandstone and sandy chert.

Dolomite: hard, aphanitic, thick-bed ded, light-brownish-gray to pale- brown (10YR 5/1-5/2); contains chert pebbles as much as 20 mm diameter in lower third and numer ous small bits of black carbon aceous?) material, some showing organic markings.

Dolomite: sandy, local cherty, hard, very fine grained, massive, light- brownish-gray to medium-gray (WYR Q/l-N 5); locally pebbly and more cherty in lower half and notably at base. Chert at base is very finely sandy and very spicular and contains rhombic carbonate and apatite as spicule canal fillings and pellets.

Chert and dolomite: locally sandy hard poorly bedded to laminated yellowixh-gray (WYR 7/1) chert containing irregularly distributed lenses and patches of dolomite.

Dolomite: locally cherty and sandy, hard, fine-grained to aphanitic, massive, light-brownish-gray to grayish-green (10 YR 6/1 to WGY 5/2). Very irregular basal contact.

Sandstone: cherty, hard, fine-grained, pale-brown (WYR 5/2); chert very finely sandy, irregularly distributed, brownish-gray (10YR 4/1); sand at base has much phosphatic material in matrix, abundant apatite pellets, some apatite shell fragments, and numerous small pebbles of sandy and spicular chert; contains numerous tiny black globules (M30 microns), generally clustered, that appear amber under an oil immersion lens and may be petroliferous matter. Irregular basal contact.


0. 9 128. 55

. 6 129. 15

Acid in soluble

Radio- metric eU

Chemical U

3. 5 132. 65

2. 5 135. 15

1. 4 136. 55

1. 3 137. 85

1. 2 139. 05

9. 7 148. 75

4. 0 152. 75

2. 8 155. 55

. 8 156. 35



Bed Description

G-14_-_-____- Grandeur Member of Park City Formation:Dolomite: hard, aphanitic, massive,

light-brownish-gray (10 YR 6/1) to yellowish-gray (10 YR 7/1); contains irregular streaks of fine sand. Angular to subrounded sand at top includes chert grains, including those of the peculiar variety of chert found in bed G-12, and numerous small apatite shell fragments, pellets, and spicule canal fillings; matrix consists of dolomite rhombs and corroded quartz and apatite grains; some pebbles of carbonate are present.

13-__------ Sandstone and dolomite: irregularlyintermixed dolomitic hard fine grained sandstone and sandy aphanitic dolomite; light-yellowish- brown (10 YR 6/4) to very pale orange (10 YR 8/2).

12-___--_,_ Chert: dolomitic, hard, pale-yellowish- brown (IOYR 6/2). Thin section reveals numerous quartz grains and much chert as grains, pebbles, or re placements in a fine dolomite matrix. Chert is characterized by coarse texture and considerable dust that is concentrated chiefly in lines or bands, many of which clearly show crystal forms of quartz; clastic quartz grains not common to chert areas. Un dulating basal contact.

11_________ Dolomite: hard, aphanitic, massive,light-brownish-gray (IOYR 6/1). Ir regular basal contact.

10___._____ Sandstone and dolomite: interlayeredand intermixed hard fine-grained sandstone and very sandy dense dolomite; poorly bedded, pale-brown (7.5 YR 6/2). Strongly undulating basal contact.

9_________ Dolomite: hard, aphanitic, massive,light-brownish-gray (10 YR 6/1).

8-------._ Dolomite: hard, aphanitic, light- brownish-gray (5YR 6/1); basal 0.8 ft, softer and shaly, forms undercut in cliff, and contains pencillike flat limonite concretions. Gradational basal contact.

7_ ________ Dolomite: hard, aphanitic, massive tothick-bedded, light-brownish-gray (5YR 6/1); contains 0.3 ft very fine sandy zone near top.

6_-_-__.__ Dolomite: hard, aphanitic, poorly bed ded to massive, light-brownish-gray (10YR 6/1); contains some crosscutting sandstone stringers and a fine dolomitic sandstone zone at the top.

5_________ Dolomite: hard, aphanitic, massive,yellowish-gray (10 YR 7/1); contains several thin (0.1-0.2 ft) layers and some crosscutting stringers of clean fine-grained yellowish-gray (10 YR 7/1) sandstone having abundant quartz overgrowths; numerous small grains of zircon and tourmaline, and some clastic carbonate. Irregular basal contact.

4.________ Dolomite: hard, aphanitic, massive,yellowish-gray (IOYR 7/1); hackly weathering in middle. Irregular basal contact.

Thick ness

Cumulative thickness

(feet) Sample

Uranium

Acid in soluble

Radio- metric eTJ

Chemical U

6. 5 162. 85

2. 5 165. 35

1. 0 166. 35

2. 0 168. 35

1. 8 170. 15

4. 0 174. 15

1. 8 175. 95

4. 0 179. 95

4. 5 184. 45

8. 0 192. 45

5. 5 197. 95


Shell Canyon, Mont., lot 1214~~Continued

Bed

G-3.

Q-l-

DescriptionGrandeur Member of Park City Forma

tion ContinuedSandstone: hard, quartzitic, fine- to

medium-grained, massive, medium- light-gray (N 6). A very clean quartz sandstone having almost com plete destruction of porosity by over growths; grains fairly well rounded; small zircon grains common; con tains little tourmaline, leucoxene, and chert (as grains). Irregular basal contact.

Dolomite: hard, aphanitic; upper half massive; lower half thin-bedded, pos sibly argillaceous, and in cliff, weath ers to form undercut; very pale brown (IOYR 7/2); finely sandy at base and locally cherty.

Quadrant Formation, top bed only:Sandstone: hard, fine-grained, mas sive, locally crossbedded, pale-brown (SYR 5/2). Grains mostly quartz having dominant overgrowths; lo cally dolomite cement rather than quartz overgrowths; clear coarser dolomite disseminated through rock. Irregular basal contact.



3. 5 201. 45

Uranium

Acid in soluble

Radio- Chemical metric eV U

3. 5 204. 95

8.0 8. 0

Aspen Valley, Mont., lot 1215[Retort and Tosi Members of Phosphoria Formation sampled in hand trench near top of ridge on west side of Aspen Valley, SEJ4SEJ4 sec. 11, T. 6 S., R. 1 E., Madison

County, Mont., on overturned limb of Madison Range syncline, in August 1947. Beds strike N. 45° E. and dip 55° NW. Measured by R. W. Swanson and sampled by J. A. Mann and J. O. Evans. Analyzed for PaOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Oeol. Survey]

Bed

Us-20.

19.

To-18.

DescriptionUpper member of Shedhorn Sandstone; top

not exposed:Sandstone: carbonatic, fine-grained,

medium-hard, light-brownish, gray (5Y726/1) to light-gray (N 7); has indistinct bedding. Contains patches of dusky-brown (5 YR 2/2) quartzite similar to that constituting under lying bed. Gradational basal con tact. Overlying beds are covered.

Sandstone: cherty, hard, fine- to very fine grained, brownish-gray (5YR 4/1) to dusky-brown (5YR 2/2). Quartz angular to well rounded, not well sorted; chert, about 40 percent of rock, forms matrix for sand; spicules common, some large (l/2-}i mm wide); some rounded grains of chert; apatite about 5 per cent, mostly light- to dark-grayish- brown pellets, some clear shell frag ments and brown sponge-spicule canal fillings. Irregular basal con tact.

Tosi Chert Tongue of Phosphoria Forma tion; contains thin tongue of Retort Phos- phatic Shale Member:

Chert: hard, thin-bedded, dark-gray (W3) to brownish-black (5YR 2/1); contains several thin layers (0.06 ft) of fissile moderate-brown (5YR 4/4) mudstone in lower half and 10 to 12 mudstone partings in upper half; contains vuggy carbonatic concre tion lined with calcite crystals in top foot. Gradational basal contact.


Thick ness (feet)

2. 1


(feet) Sample

Uranium

Acid in soluble


2. 1

75 2. 85 RWS-43-47 1. 3 90. 1 0. 0005

4. 2 7. 05 42-47 . 9 81. 8 . 0005


Aspen Valley, Mont., lot 1215 Continued

Bed Description

Tosi Chert Tongue of Phosphoria Forma tion; contains thin tongue of Retort Phos- phatic Shale Member Continued

To-17________ Chert: dark-gray (N3), thin-bedded,hard, brittle; 0.7-ft-thick layer of chert at base, thin-bedded and con tains 10 partings of soft fissile gray ish-brown (5YR 3/2) mudstone in upper part.

16-------- Chert and mudstone: hard fissile tothin-bedded dark-gray (N 3) chert (75-80 percent) and 15 interbedded layers of soft fissile to thin-bedded grayish-brown (5YR 3/2) mudstone; 3-in. mudstone layers at middle and top; chert thicker bedded in lower third.

Rt-15-------- Mudstone: soft, fissile to thin-bedded,brownish-gray (5YR 4/1) to grayish- brown (5YR 3/2); more fissile in lower third.

14-------- Phosphorite: cherty, hard, thin-bed ded, medium coarsely oolitic and coarsely nodular, medium-dark-gray (N 4). Oolites light brown, com monly cherty; several have fossil nuclei; nodules light to medium brown, mostly structureless but rich in cherty sponge spicules; fine quartz grains common. Irregular basal contact.

13_------- Carbonate rock: cherty, hard, thin- tothick-bedded, brownish-gray (5RY 4/ 1); thin dark-gray (N 3) chert lenses. Carbonate laminated, mostly microcrystalline, rhombic in cavity fillings and in cherty spots; chert microcrystalline, disseminated throughout but more abundant in some layers; quartz silt fairly common, angular.

To-12__ ______ Chert and mudstone, interbedded:fissile to thin-bedded hard brownish- black (5YR 2/1) chert (85 percent) and 17 interbedded layers of hard fissile dusky-brown (SYR 2/2) mudstone. Two-in. shear zone about 1 ft above base strikes N. 5° W. and dips steeply west. Gradational basal contact.

11 ________ Chert and mudstone, interbedded:dark-gray to brownish-black (N 3 to SYR 2/1) hard fissile to thin- bedded chert (75 percent of unit) and 17 interbedded layers of dusky- brown (5YR 2/2) to grayish-brown (5YR 3/2) hard fissile mudstone. Gradational basal contact.

10________ Chert and mudstone, interbedded:hard fissile to thin-bedded dark-gray (N 3) to brownish-black (5YR 2/1) chert (80 percent) and 13 inter bedded layers of hard fissile dusky- to grayish-brown (5YR 2/2- 3/2) mudstone. Thinner bedded in bot tom foot and at 2.3-4.0 ft above base. Gradational basal contact.

9--_--___ Chert: hard, fissile to thin-bedded (thicker in upper half), dark-gray to brownish-black, and eight hard fissile brownish-gray mudstone part ings and a 3-in. mudstone layer at 0.8 ft above base.


Thick ness (feet)

2. 5

Cumulativethickness

(feet)

Uranium

Sample

9. 55 RWS-41-47

PaOs

0. 6

Acid in soluble

Radio- metric eU

Chemical U

4. 45 14. 0 40-47

84. 0 0. 0005

78. 0 . 0005

55 14. 55

25 14. 8

39-47

38-47

1. 3

23.5

75. 4 001

31. 4 . 007 0. 006

1.0 37-47 . 5 37. 6 . 0005

4. 55 20. 35 36-47 . 5 50. 6 . 001 . 000

4. 45 24. 80 35-47 .7 82. 1 . 0005

4. 5 29.30 34-47 . 7 82. 4 . 0005

2. 25 31. 55 33-47 .5 84. 9 .0005


Aspen Valley, Mont., lot 1215 Continued

Bed

Ls-1.

Description

Retort Phosphatic Shale Tongue of Phos- phoria Formation:

Phosphorite: medium hard to friable, very finely to very coarsely pelletal, medium-dark-gray (2V 4) to dusky- brown (5YR 2/2) (very light brown in thin section). Contains very abundant fossil nuclei in both pellets and oolites; oolites common but not abundant; microcrystalline chert common in matrix of pellets, which are not closely packed, and as fossil filling. Gradational basal contact.

Phosphorite: medium-grained, soft to friable, laminated, grayish-black (N 2); contains considerable amounts of grayish-brown (5YR 3/2) mud near base and top.

Mudstone: grayish-brown (5YR 3/2), thin-bedded, medium-soft. Fairly sharp basal contact.

Carbonate rock: hard, thin- to thick- bedded, brownish-gray (5YR 5/1), microcrystalline, basal 0.2 ft soft, silty and clayey; basal contact some what gradational.

Mudstone: carbonatic, soft, clayey, not bedded, grayish-brown (5YR 3/2) to brownish-black (5YR 3/1).

Phosphorite and mudstone: soft, friable medium-grained thin-bedded dark- gray (N 3) phosphorite 0.4 ft thick overlying 0.2 ft soft thin-bedded brownish-gray (5YR 4/1) to brownish- black (5YR 2/1) clayey mudstone; some mudstone partings in phos phorite.

Phosphorite and sandstone: medium- hard medium-pelletal light-gray (N 7) sandy phosphorite 0.25ft thick overlying 0.3-ft hard fine- to medi um-grained light-brownish-gray quartzitic phosphatic sandstone. Phos phorite about one-half pelletal; pel lets and quartz grains in somewhat darker phosphatic groundmass and concentrated in layers; overgrowths on most quartz in the sandstone; phosphate chiefly pelletal but also as matrix between quartz grains.

Lower member of Shedhorn Sandstone, basal bed:

Sandstone: carbonatic, light-brownish- gray (5YR 6/1), medium-hard, fine- to medium-grained. Underlying beds not exposed.


Thick ness (feet)

Cumulativethickness

(feet)

Uranium

Sample

1. 6 33. 15 RWS-32-47 31.0

Acid in- Radio- soluble metric eU

11. 8 0. 009

Chemical U

0. 008

33. 45

45 33. 9

83 34. 73

35. 43

36.03

31-47

30-47

29-47

28-47

27-47

26.9

1. 4

3. 7

14. 6

18. 0 . 015

72. 3 . 003

15. 4 . 0005

56. 7 . 005

37. 0 . 010

. 014

.003

.004

55 36. 58 26-47 21. 3 38. 9 . 007 . 006

37. 38 25-47 1.6 92. 9 . 0005

West Fork of Gallatin River, Mont., lot 1216[Part of Phosphoria and Shedhorn Formations sampled and described from natural exposure and hand trench on mountain slope about 300 ft above north bank of West Fork

of Gallatin River in NWJ.4SEH sec. 32, T. 6 S., R. 4 E., Gallatin County, Mont., from upturned strata south of Gardiner thrust fault, in September 1947. Beds strike N. 35° W., and dip 45-50° SW. Measured by R. W. Swanson and sampled by J. A. Mann and J. G. Evans. Analyzed for P2 Os and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

Us-32.

Description

Upper member of Shedhorn Sandstone; top not exposed:

Sandstone and chert: poorly exposed, not logged in detail. Quartzite con taining interbedded chert and many crosscutting sandstone columns as much as 3 in. in diameter and 1-3 ft long.

Thick- Cumulativeness thickness(feet) (feet)

Uranium

Sample P20 5Acid in

solubleRadio-

metric eVChemical

U

4.0 4. 0


West Fork of Gallatin River, Mont., lot 1216 ContinuedChemical analyses (percent)

Bed Description

Upper member of Shedhorn Sandstone; topnot exposed Continued

Us-3!________ Chert: poorly exposed, not logged indetail; contains crosscutting quartzite columns similar to those in bed Us-32.

30________ Sandstone: hard, fine-grained, thin- tothick- but irregularly bedded, light- brownish-gray (5YR 5/1); contains lenses of very finely sandy chert and columns gf brownish-gray (5YR 4/1) cherty quartzite.

29________ Sandstone: hard, fine- to medium- grained, poorly bedded, light- brownish-gray (5YR 5/1); con tains chert nodules and lenses and columns like those in bed Us-31. Irregular basal contact.

28________ Limestone: medium-hard, thin- andpoorly bedded, light-brownish-gray (5 YR 6/1); contains columns of cherty quartzite, some of which cross entire bed. Iregular basal contact. Lime stone microcrystalline; sandstone medium- to fine-grained, angular to subrounded, cherty, phosphatic, and moderately calcareous; quartz shows some overgrowths and some corro sion by chert and calcite of matrix; chert grains common and comprise most of matrix; some sponge spicules evident; phosphate occurs as apatite pellets and nodules, shell and bone fragments (some anisotropic), sponge-spicule fillings, and clear grains of uncertain origin; calcite locally abundant and coarsely crystalline but most is finely crys talline and irregularly disseminated; some veinlets in sharp contact with adjoining limestone.

Tosi Chert Tongue of Phosphoria Forma tion:

To-27_-----__ Chert: thin-bedded, hard, brittle, me dium-light-gray (N 6); contains many crosscutting quartzite columns, some 3 ft long, and some lenses of fine-grained quartzite. Basal con tact not exposed.

26_--_--__ Covered; thickness approximate. Overlying beds measured about 50 ft lower on hillside than beds described below.

25__-____^ Chert: brittle thin-bedded medium- gray (N 5) chert; contains some quartzite in basal 0.15 ft which is overlain by 0.2-ft fissile light- brownish-gray (5YR 5/1) mudstone; top 3.0 ft contains crosscutting fine grained sandstone columns as much as 5 in. in diameter and 4 in. or more apart. Lenticular vuggy carbonate concretions as much as 3 in. thick and 6-8 in. across occur 1.5, 4.0, and 7.5 ft above base.


Uranium

Acid in- Radio- Chemical soluble metric eU U

2. 0

10. 5

2. 0

6.0

16. 5

18. 5

19. 2

5. 5 24. 7

25. 2

8. 85 34. 05 RWS-63-47 0.8 90. 1 0. 0005


West Fork of Gallatin River, Mont., lot 1216 Continued

Bed

To-24_.

23.

22.

21.

Rt-20.

19.

18.

Description


Sandstone: cherty, hard, fine- to me dium-grained, grayish- to dusky- brown (5YR 3/2); very cherty at base. Quartz moderately rounded to angular; overgrowths common al though matrix is composed mostly of chert; chert is brown and dusty and contains numerous siliceous sponge spicules; clear to dusty and light- brown to black apatite pellets, clear to medium-brown shell fragments, and brown spicule fillings of apatite are common.

Chert: hard, brittle, fissile to thin- bedded, brownish-black (5YR 2/1); contains 1.0 ft of soft fissile to thin- bedded pale-brown (5YR 5/2) mudstone that forms 27 rather uniformly spaced layers.

Chert and mudstone, interbedded: hard, brittle fissile to thin-bedded dark-brownish-gray (5YR 3/1) chert (75 percent) containing 15 layers totaling 0.9 ft of soft fissile pale- brown (5YR 5/2) mudstone. Thicker layers of mudstone occur 0.7, 2.3, and 2.9 ft above base and commonly contain thin (0.01 ft) lenses of chert.

Chert and mudstone, interbedded: hardbrittle fissile to thin-bedded dark-brownish-gray (5YR 3/1) chert (75 percent) containing 23 layers totaling 1.2 ft of soft fissile brown ish gray (5YR 4/1) mudstone, mudstone layers thicker and more closely spaced at 1.2-2.8 ft above base. Slightly irregular basal contact.


Phosphorite: cherty, sandy, hard, finely pelletal to finely nodular, dark- gray (N 3). Chiefly apatite pellets and nodules (40 percent) and fine sand (25 percent) in a cherty matrix (35 percent). Apatite nodules are very silty and generally rich in sili ceous sponge spicules; pellets are mostly dusty but some are clear; apatite shell fragments and spicule fillings are common; quartz grains are mostly subangular to rounded; chert grains are common; chert ce ment is mostly dusty brown and rich in sponge spicules and corrodes both quartz and apatite. Irregular basal contact.

Mudstone: medium-hard, thin-bedded (upper third fissile), grayish-brown (5YR 3/2) to moderate-brown (5YR 4/4),

Chert (?): medium-hard to soft, thin- bedded, locally fissile, weak-yellow ish-orange (10 YR 7/6) to moderate- yellowish-brown (1QYR 5/4); 0.4 ft dark-brownish-gray (WYR3/2) layer near middle. Appears to be com posed chiefly of cryptocrystalline chert groundmass containing angular quartz silt and lesser amounts of car bonate, muscovite, and carbona ceous material.



Uranium

Sample

0. 65 34. 7 RWS-62-47

Acid in- Radio- Chemical soluble metric eTJ II

2. 0 89. 2 0. 0005

5. 75 40. 45

3. 4 43. 85

61-47

60-47

.7 84. 8 . 0005

.6 90. 7 . 0005

4. 45 48. 3 59-47 .7 91. 0 . 0005

48.6 58-47 14. 9 56. 3 .006 0.005

1. 35

1. 8

49.95

51.75

57-47

56-47

9 81. 1 . 001

3. 1 . 001



Bed

Rt-17.

14.

Ls-13.

12.

11.

Description

Retort Phosphatic Shale Tongue of Phos- phoria Formation Continued

Chert (?): soft to medium-hard, fissile to thin-bedded, moderate-yellowish- brown (10 YR 5/4) to brownish-black (10 YR 2/1). Chiefly cryptocrystalline chert containing quartz silt and car bonaceous material, as does bed Rt- 18. Contains very fine phosphate pellets.

Mudstone: medium-hard to soft, fissile to thin-bedded, brownish-gray (5YR 4/1) to grayish-brown (5YR 3/2).

Phosphorite: cherty, medium-hard, medium- to very coarsely oolitic (60 percent) to pelletal, medium-gray (N 5) to brownish-gray (5YR 4/1). Oolites and pellets pale brown, some have quartz or fossil nuclei; matrix composed of pale-brown cryptocrys talline chert near oolites and clear fine to medium-coarse comb- and flamboyant-structure quartz in cen tral areas between loosely packed oolites.

Phosphorite: medium-hard to friable, poorly bedded, fine to coarsely oolitic-pellatel, brownish-black (5YR 2/1) to grayish-black (N 2). Basal 0.2 ft sandy (medium-grained quartz) and moderately pelletal to nodular; contains numerous shell fragments, all in a phosphatic matrix much like that of pellets; remainder com posed of fairly closely packed ap atite oolites and pellets, containing numerous subrounded quartz grains cemented by cryptocrystalline chert. Gradational basal contact. Contains L/ingula.

Lower member of Shedhorn Sandstone: Sandstone: phosphatic, medium-hard

(locally soft), thick-bedded, fine to medium-grained, moderate-yellowish- brown (IOYR 5/4) to brownish-gray (IOYR 4/1). Overgrowths on quartz very common; apatite (20 percent) occurs as medium to coarse pellets but also commonly as shell fragments; rounded grains of chert are common; some secondary chert occurs. " Grada tional basal contact.

Sandstone: medium-hard, poorly bedded, medium-grained, pale-brown (5 YR 5/2); contains pebbles of mudstone and chert at base. Quartz has dom inant overgrowths; chert grains are very common; apatite is common, chiefly as shell fragments but also as pellets and rims on quartz grains. Irregular basal contact.

Mudstone and sandstone: soft fissile grayish-brown (10 YR 4/2) mudstone containing many crosscutting 0.1- to 0.2-ft diameter hard fine-grained sand stone concretions. Quartz in sand stone has abundant overgrowths; apatite (10 percent) occurs as pellets, shell fragments, rims on quartz grains, sponge spicule fillings, and matrix; some is probably secondary; chert grains are very common (5-1- percent); some dusty-brown chert cement; many grains coarsely chalcedonic. Irregular basal contact.



85 52. 6 RWS-55-47

Uranium

Acid in soluble

Radio- metric eU

Chemical U

0.8 81. 1 0. 002

2.5 55. 1 54-47 1. 1

45 55. 55 53-47 22. 2

84. 2

39.4

. 001

.008

0. 000

.008

56.25 52-47 26.2 27.0 .009 .007

1. 5 57. 75 51-47 70.2 .003 .001

1. 6 59. 35 50-47 .6 .0005 .000

1.3 60. 65 49-47 1. 1 81.3 .001 .000

709-931 O 63-



Bed Description

Lower member of Shedhorn Sandstone Continued

Ls-10-- ______ Chert, sandstone, and mudstone: 0.3 fthard, brittle sandy dusky-brown (SYR 2/2) to brownish-black (SYR 2/1) chert at base, overlain by a 0.4 ft medium-hard to soft brownish-gray (SYR 4/1) mudstone, a 0.2 ft chert like that at base, and a 0.45 ft fine grained hard dark-gray (N 3) sand stone at top. Unit contains many crosscutting chert and sandstone columns that render bedding incon spicuous. Irregular basal contact.

9_--_--_- Sandstone: cherty, hard, medium- grained, poorly bedded, light- brownish-gray (SYR 5/1). Chert occurs in irregular masses and nod ules, more abundant toward top. Unit contains many crosscutting col umnar bodies of sandstone contain ing quartz having abundant over growths, several percent apatite occurring as shell fragments, pellets, and matrix, 10 ± percent chert grains, and chert and very fine calcite ce ment. Irregular basal contact ap parently crossed by some columnar bodies.

8_--_--_- Mudstone and sandstone: soft fissile to thin-bedded moderate-yellowish- brown (10 YR 5/6) carbonatic sandy mudstone containing abundant crosscutting quartzitic sandstone columns; columns are 0.05-0.2 ft in diameter, irregular sided, and closely spaced.

7-_______ Mudstone and sandstone, interbedded:medium-hard to soft fissile to thin- bedded weak-yellowish-orange (10 YR 8/4) to light-brownish-gray (10 YR 5/1) carbonatic mudstone, interbedded with hard fine-grained thin- bedded brownish-black (SYR 2/1) sandstone; beds are lenticular. Top part locally conglomeratic; basal contact irregular.

6________ Sandstone: hard, medium-grained,thick-bedded, brownish-gray (5 YR 4/1); 2-in. zone containing chert pebbles near middle. Quartz, mod erately well rounded; has abundant overgrowths; chert grains and apa tite pellets and shell fragments com mon. Gradational basal contact.

5________ Sandstone: hard, thin- to thick- butpoorly bedded, fine-grained, medi um-gray (N 5); contains worm(?) borings. Thickness 3.2 ft a few feet below the trench.

R-4________ Chert: hard, brittle, thin-bedded, lo cally sandy, brownish- to light- brownish-gray (SYR 4/1- 5/1); lo cally shattered.



1. 35 62. 0 RWS-48-47

Acid in- Radio- Chemical PjOs soluble metric eV U

1. 5 55. 0 0. 0005 0.000

2.2 64.2 47-47 1.4 91. 9 . 001 .000

1. 15

1. 05

65.35

66. 4

46-47

45-47

2.2 87. 2 005 .000

.9 77. 1 . 0005

1. 2 67. 6 44-47 .8 95. 2 . 0005 . 000

4.3 71.9

73. 7


West Fork of Gattatin River, Mont., lot 1216 Continued

Bed

R-3.

Q-i

Description


Chert: hard, brittle, thin-bedded, lo cally sandy, brownish-gray (5YR 4/1); contains four layers totaling 0.55 ft of medium-hard fine-grained light-brownish-gray sandstone. Ba sal contact not exposed. Sandy chert near base contains 40 percent moderately rounded fine-grained quartz in a cryptocrystalline chert cement; quartz grains are commonly corroded; siliceous sponge spicules are abundant, particularly in less sandy parts; apatite pellets common, and some broken pellets and a few clusters suggest reworking of a phosphorite bed; some pellets have quartz nuclei.

Covered. Includes the contact be tween the Quadrant Formation and the strata of the Shedhorn Sandstone.

Quadrant Formation, top bed:Sandstone: medium-hard to friable,

locally hard, white (N 9), thick- bedded to massive. Not described in detail.



6. 3 80. 0

Uranium


10. 0 90. 0

10. 0 100. 0

Porcupine Creek, Mont., lot 1217[Phosphoria Formation and part of Shedhorn Sandstone and Retort and Tosi Tongues of Phosphoria Formation sampled from natural exposures and hand trench on upper

part of mountain slope H*j miles north of Porcupine Creek in NEHSE54 sec. 10, T. 78., R. 4 E., Qallatin County, Mont., from upturned strata south of Oardiner thrust fault. Beds strike N. 40° W. and dip 75° SW. Measured by R. W. Swanson and sampled by J. A. Mann and J. Q. Evans, in September 1947. Analyzed for P2O and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Oeol. Survey]


Bed

Us-23.

22.

21.

20.

Description

Upper member of Shedhorn Sandstone; uppermost beds not exposed:

Sandstone: hard, massive, fine- to medium-grained, light-brownish-gray (SYR 6/1); contains dark phosphate or chert grains, or both. Irregular basal contact. Overlying strata not exposed.

Chert: hard, brittle, thin- to thick- bedded, light-gray (N 7); contains lenses of fine- to medium-grained sandstone and many crosscutting of sandstone columns.

Sandstone: hard, fine-grained, thick- bedded, yellowish-gray (SYR 7/2) to light-brownish-gray (5YR 6/1). Some layers weather gray. Not very well exposed. Basal contact irregular.

Sandstone: hard, fine- to medium- grained, light-brownish-gray (5 YR 6/1); cherty and finer-grained near top. Quartz grains angular to mod erately rounded and have abundant overgrowths; chert grains common; apatite (4 percent) chiefly as shell fragments.

Cumulative Thickness thickness

(feet) (feet)

Uranium

Sample Ps0 6Acid

insolubleRadiometric Chemical

eU U

6. 0

2.6

4.8

6. 0

13. 4

14. 0 RWS-79-47 1. 6 93. 1 0. 0005


Porcupine Creek, Mont., lot 1217 Continued

Bed Description

Tosi Chert Tongue of Phosphoria Formation: To-19________ Chert: hard, brittle, thin-bedded, light-

brown (5YR 6/4); contains 12 interbeds of soft fissile mudstone totalling 0.3 ft thick.

18________ Chert: Like that of To-19; bed contains21 layers of interbedded mudstone totalling 0.5 ft thick.

17________ Chert and mudstone, interbedded: hardbrittle thin-bedded chert (65 percent) and soft fissile mudstone (20 layers totalling 1.3 ft); both chert and mudstone are light-brown (5 YR 6/4) ; two 0.2-ft mudstone layers in middle.

16_ _______ Chert and mudstone, interbedded:chert (70 percent) and mudstone (five layers) like that of bed To-17; 1-ft layer of chert near top and mostly mudstone below. Chert con tains considerable amounts of .coarse angular quartz silt and nearly 10

Eercent apatite as sponge-spicule llings and small pellets and in

matrix.15_ _______ Chert and mudstone, interbedded:

chert (75 percent) and mudstone (five layers) like that of bed To-17.

14_ _______ Chert and mudstone, interbedded:chert (70 percent) and mudstone (four layers) like that of bed To-17.

13_____-__ Chert and mudstone, interbedded: chert (65 percent) and mudstone (four layers) like that of bed To-17.

Re.tort Phosphatic Shale Tongue of Phos phoria Formation:

Rt-12_ _ ______ Sandstone: hard, medium-grained, thin- to thick-bedded, medium-gray (N 5); contains nearly 18 percent apatite as oolites, pellets, shell fragments, sponge-spicule fillings, and rims on quartz grains. Chert is common as grains and as matrix. Mudstone partings occur near base. Basal contract irregular.

!!________ Mudstone: carbonatic. medium-hard tosoft, thin-bedded to fissile, light- brown (SYR 6/4) to dusky-yellow (5Y 6/4); softer and thinner bedded higher in bed; locally it is a muddy carbonate rock containing 25 percent coarse angular quartz silt, mica flakes, and dark carbonaceous to phosphatic matrix. Many small almond-shaped phosphatic concre tions (}£ in. long) occur in lower half.

10________ Mudstone: carbonatic, medium-hard,thin-to thick-bedded, light-brownish- gray (5YR 6/1).

9________ Mudstone: soft, fissile to thin-bedded,dusky-yellow (5F6/4) to light-brown (SYR 6/4).

8_ _______ Phosphorite: pherty, medium-hard,medium to coarsely oolitic, pinkish- gray (SYR 7/1). Contains thin (0.05 ft) fissile mudstone layer at base. Oolites (commonly having quartz nuclei) and pellets of apatite are immersed in dusty cherty cement that is coarser and clearer near cen ters of interstitial areas. Basal con tact irregular.



(feet) (feet) Sample

4. 6 18. 6 RSW-78-47

3. 9 22. 5 77-47

3. 6 26. 1 76-47

Uranium

Acid JRadiometric Chemical insoluble eV U

0. 8 82. 1 0. 0005

1. 55 27. 65 75-47

.4 86. 0 . 0005

.9 84. 8 . 0005

3. 3 87. 0 . 0005

1. 0 28. 65 74-47

. 95 29. 6 73-47

1. 65 31. 25 72-47

. 6 31. 85 71-47

.8 87. 4 . 0005

.6 86. 0 .0005

1. 1 87. 4 0005

6. 9 76. 6 . 001

. 8 32. 65 70-47 1. 4 60. 8 . 001

. 7 33. 35 69-47

2. 9 36. 25 68-47

1. 0 37. 25 67-47

.4 45.5 .0005 ____-

1.6 81.8 .002 ..____.

22. 9 35. 0 . 009 0. 007


Porcupine Creek, Mont., lot 1217 ContinuedChemical analyses (percent)

Bed Description


Rt-7________ Carbonate rock and sandstone: medi um-hard massive microcrystalline pale-brown (5YR 5/2) cherty carbo nate rock containing many crosscutting hard fine- to medium-grained light-brownish-gray (5F.R6/1) cher ty sandstone columns that average 0.05-0.2 ft in diameter and 0.3 ft apart. Sandstone poorly sorted, grains an gular to moderately rounded; chert matrix mostly microcrystalline; apa tite common as pellets (clear to dark brown and dusty), fossil fragments, rims on quartz grains, and sponge- spiculefillings; chert grains common; carbonate fairly common as rounded grains and small secondary rhombs.

6________ Mudstone: soft, fissile, dusky-yellow(5 Y 6/4); contains many crosscutting columns of fine-grained p'ale-brown (10 YR 6/2) sandstone about 0.1 ft in diameter that appear to project into overlying bed Rt-7 and are lithologically similar to those of bed Ls-5.

Lower member of Shedhorn Sandstone: Ls-5-----_-_ Sandstone: hard, cherty, fine- to

medium-grained, brownish-gray (5YR 4/1), locally calcareous; con tains many crosscutting chert col umns averaging 0.1 ft in diameter and 0.5 ft apart and scattered fossils (Lingula?) near top. Quartz grains (50 percent) immersed in dusty crypto- to microcrystalline chert (35 percent) and commonly corroded by chert; contains 5-10 percent chert (?) grains and apatite as pellets, shell fragments, rims on quartz grains, and sponge-spicule fillings; siliceous sponge spicules common in chert. Irregular basal contact.

4-------- Sandstone: carbonatic, hard, medium- grained, poorly bedded, medium- gray (N 5) to light-brownish-gray (5YR 6/1); locally conglomeratic at 5.7 ft above base and in top foot.

3________ Sandstone: 1.0 ft fine- to medium- grained hard yellowish-gray (5YR 7/2) quartzitic sandstone overlain by 0.5 ft medium-grained hard light- brownish-gray (5YR 5/1) calcareous sandstone containing many gastro pods and chert pebbles at top that are as much as 1 in. across. Quartz has abundant overgrowths on dusty- rimmed grains, and calcite dust and very small crystals are abundant at old grains boundries and in matrix between grains. Chert grains and pellets and shell fragments common.


(feet) (feet)

Uranium

Sample

1. 25 38. 5 RWS-66-47

Acid Eadiometric Chemical PsO 6 insoluble eU U

0. 8 59. 3 . 0005

39. 1 65-47 1. 8 78. 5 . 0005

64-47 2. 6 86. 7 . 0005

9. 5

1. 5

49. 3

50. 8


Porcupine Creek, Mont., lot 1217 Continued

Bed

Ls-2.

Q-l.

Description


Sandstone and chert: top and bottom thirds composed of cherty sandstone; middle third, sandy chert; all are hard, thin- to thick-bedded; sand stone (65 percent) fine- to very fine grained, yellowish-gray (5Y 7/2) (darker upward), having chert ce ment, apatite pellets and sponge- spicule fillings, and siliceous sponge spicules; carbonate occurs as rounded grains and very fine matrix; chert irregularly bedded to concretionary, light-gray (N 7). Basal contact somewhat sheared.

Quadrant Formation, top bed:Sandstone: mostly medium-hard (locally

hard) or friable, massive, fine-grained yellowish-gray (2.5 Y 8/1) to white (N 9); irregularly cherty near top. Quartzite near top nearly all quartz and also minor tourmaline, titanite, magnetite (?), and chert; quartz subangular to well rounded and has extensive overgrowths; one thin layer has fine silty matrix. Chert near top is both microcrystalline and fairly coarse «>£ mm), and is partly chalcedonic and coarsely flamboyant; dust lines, more or less concentric to nuclei of crystallization, outline euhedral forms.


Thickness (feet)

11. 4

Cumulativethickness

(feet)

62. 2

Uranium

SampleAcid


eU U

10. 0 10. 0

Jack Canyon, Mont., lot 1218

[Part of Phosphoria, Shedhorn, and Park City Formations sampled and described from cliff exposures and small hand trench about 900 ft above Creek on north side of Jack Creek Canyon in SEJ4NEJ4 sec. 35, T. 5 S., R. 1 E., Madison County, Mont., on overturned and faulted west limb of Madison Range syncline. Beds strike N. 60° E. and dip 45 N W. Measured by R. W. Swanson and sampled by J. G. Evans in September 1947. Analyzed for uranium by U.S. Geol. Survey, and for other constituents by U.S. Bur. of Mines. LOI, Loss on ignition]

Bed Description

Dinwoody Formation, basalbeds:

D-41____ Mudstone: soft, weak-yel lowish-orange (2.5Y 7/4) to pale-brown (2.5Y 5/2), thin- to thick-bedded; contains thin layers of fine-grained ripple-marked sandstone and of aphanitic g'-ay limestone.

40_. __ Sandstone: carbonatic, muddy, soft to medium- hard, very fine grained, light-brownish-gray (5 YR 6/1); weathers yellowish- gray; contains 0.1 ft chert- pebble conglomerate at base and a few thin mudstone partings.



(feet) (feet)

Uranium

SampleAcid

insoluble AljOs LOIRadio- Chemical

metric eU U

6. 0 6. 0

1. 6 7. 6


Jack Canyon, Mont., lot 1218 ContinuedChemical analyses (percent)


Bed Description (feet) (feet)

Upper member of ShedhornSandstone:

Us-39___ Sandstone: calcareous, con- 5. 2 5. 2 glomeratic, hard, thick- bedded to massive, fine- to medium-grained, light- brownish-gray (5 YR 6/1); pebbles are composed of chert.

38_ Sandstone: irregularly 3. 0 8. 2 bedded, medium-grained, light-brownish-gray (5 YR 6/1); contains very light gray (N 8) chert nodules; irregular basal contact.

37.__ Sandstone: hard, medium- 18. 1 26. 3 grained, massive, light- brownish-gray (5 YR 5/1); locally cherty; contains 2 in. of flat-pebble lime stone conglomerate at 7.0 and 13.3 ft above base; contains sandstone col- ums in top 2 ft; irregular basal contact.

36_ __ Sandstone: medium-hard to 12.8 39. 1 hard, thin-bedded to mas sive (thinner-bedded to ward top), medium- grained, light-gray (N 7) to light-brownish-gray (5YR 6/1); contains flat- pebble limestone con glomerate at base and thin-bedded chert at top. Irregular basal contact. Overgrowths on quartz grains include consider able amounts of microcrystalline rhombic car bonate at margins of old grains or between present grains; laminae of microcrystalline carbonate and of chert present; chert and carbonate do not penetrate areas of quartz overgrowths; numerous apatite pellets present.

35___ Chert and sandstone: 1.8 8.4 47.5 ft sandstone and chert at top, underlain by 0.5 ft limestone and chert, 4 ft chert, and 2 ft moderately well-bedded cherty quartzite. Chert is hard, gen erally poorly bedded and shattered, dark-gray (N 3); sandstone is fine grained, calcareous, me dium hard, brownish gray (5 YR 4/1); contains some columnar sandstone con cretions (1-2 in. in diam eter) in the chert below the limestone. Irregular basal contact.

Uranium

SampleAcid

insoluble A12O 3 LOTRadio- Chemical

metric eV U

RWS-107-47 0. 8 68. 4 1. 6 2. 6 12. 2 0. 0005

106-47 1. 5 74. 0 1. 3 9.7 0005

105-47 1. 5 81. 3 1. 9 6.5 0005

104-47 8 85.0 9 2.6 4. 7 0005





Upper member of ShedhornSandstone Continued

Us-34___ Sandstone: hard, medium- 0. 9 48. 4 grained, light-brownish- gray (5YR 5/1).

33___ Sandstone: phosphatic, .5 48. 9 hard, thin-bedded, medi um-grained, pale-brown (5YR 5/2); apatite chiefly pelletal, but much in matrix of some thin layers; apatite shell frag ments and secondary apatite present; over growths on most quartz grains; apatite consti tutes about 20 percent of bed.

32. __ Chert; sandy, hard, thin- 1.35 50.25 bedded to nodular, medi um-gray (N 5) to dark- gray (N 3); top 3 in. contains thin layers of calcareous mudstone.

31___ Sandstone: hard, medium- 1. 2 51. 45 grained, pale-brown (SYR 5/2); cherty at base.

30___ Sandstone: hard, medium- 2.15 53.6 grained, light-brownish- gray (5YR 5/1).

29. __ Chert: sandy, hard, thin- 2.5 56.1 bedded to nodular, medi um-gray (N 5) to dark- gray (N 3); sand is fine.

28. __ Sandstone: hard, thick- 10. 5 66. 6 bedded, fine-grained, pale-brown (5YR 5/2); somewhat cherty at top.

27-.- Sandstone: hard, fine- to 9.65 76.25 very fine grained, mostly thick- but poorly, bedded, light-brownish-gray (5 YR 5/1); irregular basal con tact. Six ft above base most quartz has over growths; apatite (5-10 percent) occurs mostly as pellets.

Tosi Chert Tongue of Phospho- ria Formation; contains two thin tongues of Retort Phos phatic Shale Member of Phosphoria Formation in lower part:

To-26___ Chert: variably sandy, 2.5 78.75 hard, poorly bedded, dark-gray (N 3); contains irregular lenses of sand stone.

25. __ Sandstone: cherty, hard, 2.5 81.25 poorly bedded, fine- to medium-grained, pale- brown (5YR 5/2); con tains apatite pellets.

24. __ Chert: hard, thin-bedded, .9 82.15 dark-gray (N 3).

23_ _ _ Sandstone: cherty, hard, . 3 82. 45 fine-grained, pale- brown (SYR 5/2).

Uranium

Sample PjOsAcid

insoluble Al2 Oa LOTRadio- Chemical

metric eU U

RWS-103-47 1. 8 0. 8 2. 1 2. 1 0. 0005

102-47 1. 4 75. 3

101-47 2. 1 89. 3

1. 1

9 1. 3

9. 0

1. 8

0005

0005

100-47 1. 3 9 3. 5 2. 0 0005



UraniumCumulative

Thickness thickness Bed Description (feet) (feet)

Tosi Chert Tongue of Phospho-ria Formation; contains twothin tongues of Retort Phos-phatic Shale Member ofPhosphoria Formation inlower part Continued

To-22__. Chert: fissile to thin-bed- 3.9 ded, hard, dark-gray (2V 3); contains 17 fissile brownish-gray (5YR 4/1) mudstone partings and 0.3 ft of thin-bedded mudstone at base.

21__. Chert: hard, thin-to thick- 5.25 91.6 bedded, dark-gray (N 3); contains a few 0.1-ft layers of fissile to thin- bedded brownish-gray (SYR 4/1) mudstone. Contains considerable amounts of very fine sand and silt and many siliceous and phosphatic sponge spicules.

20_ __ Chert: hard, thin-bedded, 6.9 98.5 dark-gray (N 3); contains 27 layers totaling 0.6 ft of fissile to thin-bedded dusky-brown mudstone.

19___ 'Phosphorite: sandy, cherty, . 17 98. 67 coarsely pelletal, hard, medium-dark-gray (N 4). Apatite pellets in cherty phosphate cement; qaurtz nuclei common in pellets; siliceous sponge spicules common; chert has locally replaced much apatite.

18. __ Chert and mudstone, inter- 2.4 101.07 bedded: fissile to thin- bedded hard grayish-black - chert (75 percent)interbedded with soft to me dium-hard dusky-brown (SYR 2/2) mudstone.

Rt-17. _ _ Phosphorite: cherty, hard, . 5 101. 57 coarsely oolitic and pel letal to coarsely nodular, grayish-black (TV 2). Ap atite mostly oolitic but forms numerous pellets and nodules, in a cherty phosphate cement; pellets form nuclei of many ooli tic grains; chert has ir regularly replaced much of the matrix and the oolites; contains siliceous sponge spicules. Irregu lar basal contact.

16_ __ Mudstone: carbonatic, me- . 9 dium-hard, thin-to thick- (3.25) bedded, laminated, brown ish-gray (SYR 4/1). This bed and 1.6 ft of under lying chert repeated by near-bedding-plane fault. Original sampled bed 3.25 ft thick; fault interpreta tion worked out after sampling. Probable com position: P2Os, 1.0; acid insoluble, 49.0 ±; A12O3, 2.5; Fe2O3, 3.5; loss on ignition, 21.5.

SampleAcid

insoluble Ala Os LOIRadio- Chemical

metric eU U

86. 35 RWS-99-47 6 85. 0 3. 1 5. 1 3. 0 0. 0005

98-47 1. 3 83. 1 1. 8 4. 3 4. 1 0005

97-47 9 84. 5 3. 2 5. 5 2. 9

96-47 18. 9 44. 0 1. 3 2. 9 2. 2

001

004

95-47 1. 2 81. 3 6. 0 5. 2

94-47 22. 9 37. 4 1. 4 2. 6

4. 2 001

1.8 006 0. 005

102. 4793-47

(1.0?) (49.0?) 67. 8

(2.5?) 3. 6

(3.5?) 4. 1

(21.5?) 11. 9 0005


Jack Canyon, Mont., lot 1218 Continued

Bed Description

Tosi Chert Tongue of Phospho- ria Formation; contains two thin tongues of Retort Phos- phatic Shale Member of Phosphoria Formation in lower part Continued

To-15--_ Chert: fissile to thin-bedded, brittle, brownish-black (5YR 2/1); contains 15 layers totaling 0.4 ft of fissile brownish-black mudstone; somewhat thicker-bedded and less mudstone upward. Gra- dational basal contact.

14___ Chert: fissile to thin-bedded, brittle, medium-dark-gray (N 4), contains 15 layers totaling 0.5 ft of fissile dusky-brown mudstone and 0.1 ft mudstone bed 2.4 ft above base. Gra- dational basal contact.

13___ Chert: fissile to thin-bedded, brittle, dark-gray (N 3); contains 0.3 ft -(15 layers) of fissile dusky-brown (5YR 2/2) mudstone.

Retort Phosphatic Shale Tongueof Phosphoria Formation:

Rt-12.__ Phosphorite: soft, friable, poorly bedded, coarsely oolitic, dusky-brown (5YR 2/2).

11___ Carbonate rock: muddy, soft, grayish-brown (5 YR 3/2). Underlain by 4-ft andesite porphyry sill having a plane, transect ing contact.

10._ . Sandstone and phosphorite: 0.4 ft sandy medium- to coarsely oolitic and pelletal dark-gray (N 3) phosphorite gradationally underlain by a 0.4 ft hard, fine-grained brown ish-gray (5YR 4/1) sand stone. Apatite oolites and pellets occur in and are dominated by darker brown phosphatic ma trix ; subangular quartz particularly common in some layers; some re placement of quartz by apatite. Subrounded quartz grains of the sand stone have abundant overgrowths; apatite (12 percent) occurs chiefly as pellets and as matrix, much of which is recrystallized and colorless; chert grains common. Irregular basal contact.


Uranium

Thickness (feet)

Cumulativethickness

(feet) Sample P205Acid

insoluble Fe2 Os LOIRadio- Chemical

metric e~U U

4. 05 106. 52 RWS-92-47 0. 6 87. 3 4. 7 4. 7 2. 4 0. 001

4. 6 111. 12 91-47 86. 9 4. 5 4. 9 2. 4 0005

4. 4 115. 52 90-47 6 87. 5 4. 3 4. 1 2.5 001

1. 15 116. 67

117. 07

0. 8 117. 87

89-47 28. 8 19. 0 1. 4 1. 9 4. 5

24. 9 4. 7 2. 3 32. 6

85-47 12. 7 61. 3 1. 9 3. 0 1. 7

010

001

004

009

004



Uranium

Bed Description

Lower member of ShedhornSandstone:

Ls-9_-__ Sandstone: hard, fine grained, thin-bedded to massive, light-brownish- gray, irregular basal con tact.

8-_-_ Sandstone: hard, thin- to thick-bedded, fine- to medium-grained, light- brownish-gray (5 YR 5/ 1); top 0.7 ft thin-bedded and cherty.

7_ ___ Sandstone and chert: 1.9 ft, hard fine-grained thick- bedded light-brownish- gray (5YR 5/1) sandstone having 0.3 ft thick layers of hard brittle fissile to thin-bedded chert 0.8 ft above base and at top of bed.

6____ Conglomerate: 0.5 ft hard medium-gray (N 5) to light-brownish-gray (5 YR 5/1) chert-pebble con glomerate overlain by %- in. layers of mudstone and chert. Sandstone in conglomerate bed mostly medium grained; pebbles as much as 40 mm across. Irregular basal contact.

5____ Mudstone and sandstone: 0.3 ft muddy, calcareous medium-hard fine- grained medium-gray (N 5) sandstone overlain by 1.0 ft of soft calcareous, sandy light-brown (5YR 6/4) to dusky-yellow (5 Y 6/4) mudstone. Abun dant but incomplete quartz overgrowths on grains in sandstone; some are oscillatory, having good crystal outlines; sec ondary calcite fills re maining interstices. Contains chert grains and some apatite pellets. Gradational basal con tact.

4____ Sandstone: hard, fine grained, poorly bedded, locally cherty or calcar eous, medium-gray (N 5) to light-brownish-gray (5FE5/1). Quartz grains have abundant over growths that have good crystal outlines; second ary calcite in interstices; contains nearly 20 per cent chert grains and numerous dusty apatite pellets; overgrowths on some carbonate grains.


(feet) (feet) Sample Ps06Acid

insoluble AhOa LOIRadio- Chemical

metric «U U

4. 6 122. 47 RWS-84-47 1. 3 90. 7 2. 4 0. 0005

3. 95 126. 42

2. 5 128. 92

83-47

82-47

8 92. 1 1. 4 1. 9

94. 2 1. 0 1. 9

0005

0005

6 129. 52 81-47 2. 4 2. 8 3. 1 7.3 001

1. 3 130. 82 80-47 70. 4 6. 5 3. 2 9. 6 001

2. 2 133. 02



Bed Description


LS-3---_ Chert and sandstone: me dium to poorly bedded hard light-gray sandy chert containing interbeds and lenses of very fine grained calcareous sandstone and a few small lenses of sandy carbonate rock. Chert and carbon ate are microcrystalline and contain considerable amounts of fine-grained quartz sand and about 5 percent apatite as pellets and sponge-spicule canal fillings; chert contains abundant siliceous sponge spicules. Unit much shattered and not well exposed.

Franson Tongue of Park City Formation:

F-2_____ Carbonate rock and chert: thin- to medium-bedded hard medium-light-gray carbonate rock contain ing numerous thin interbeds, lenses, and some nodules of chert; some cherty, quartzitic sand stone layers up to 0.4 ft thick.

!-____ Dolomite: sandy, cherty, poorly bedded to massive, hackly weathering, light- brownish-gray (5YR 6/1). Dolomite microcrystal line; sand is very fine angular quartz; contains numerous apatite pellets and sponge-spicule fill ings.


(feet) (feet)

11. 5 144. 52

Uranium

SampleAcid

PaOj insoluble A1203 LOIRadio- Chemical

metric eU U

11. 0 155. 52

8. 0 163. 52

Dalys Spur, Mont., lots 1222 and 1223[Permian rocks measured and sampled near Dalys Spur, west side of Beaverhead River, T. 8 8., R. 10 W., Beaverhead County, Mont. Retort Phosphatic Shale Member

of Phosphoria Formation (lot 1222) measured in hand trench, NWJ-4SW !4 sec. 36; rest of section (lot 1223) measured in hand trench and natural exposures, SWJ4SWH sec. 36, T. 8 8., R. 10 W. Beds strike north to N. 30° E. and dip 30°-40° W. Section measured by W. R. Lowell and sampled by D. A. .Bostwick, R. L. Parker, andE. T. Rupple, in July 1947. Analyzed for PjOs, F, and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

Us-97_

To-96.

Us-95_

To-94_. Us-93_.

Description

Dinwoody-Shedhorn contact concealed by basalt flow; approximately 20 ft of Per mian rocks are covered.

Upper tongue of Shedhorn Sandstone; con tains several thin tongues of Tosi Chert Member of Phosphoria Formation:

Sandstone: hard, medium-gray (N 5), thick-bedded, fine-grained; contains scattered chert lenses that occur be tween sandstone beds; contains glauconite.

Chert: hard, brittle, medium-gray (N 5), thick-bedded; contains glauconite.

Sandstone: hard, medium-gray (N 5), thick-bedded, fine-grained; contains glauconite.

Chert: hard, gray (N 5), thick-bedded-Sandstone: cherty, hard, medium-gray

(N 5), thick-bedded, fine-grained.

Thick- Cumula-ness tive Mck-(feet) ness (feet)

Uranium

SampleAcid insoluble F

Radio- Chem.kal metric eU U

23. 7

12. 5

4.0

3.8 2.0

43. 7 WRL-286-47 2. 2 4 __ 0.001 0.000

56.2

60. 2

64.066.0

285-47 1. 5 91. 0

284-47 2. 2

. 001 . 000

. 001 . 000


Dalys Spur, Mont., lots 1222 and 1228 Continued

409


Acid insoluble

WRL-283-47 1.5 90.1 ____

282-47 1.6 89.6 ___.

281-47 2.5 87.3 ____

89. 1 _._.

78.3 __..

278-47 2.6 86.3 ....

277-47 16. 6 50. 6

45-47 3.5 80.0 __

44-47 3. 2 78. 5

Thick- Cumula- ness tive thick-

Bed Description (feet) ness (feet) Sample

Tosi Chert Member of Phosphoria Forma tion:

To-92.______ Chert: hard, light-olive-gray (5 Y 6/1), 20.4 86.4thick-bedded; contains glauconite; grades from bed below.

91______. Chert: hard, light-gray (N 7), thick- 22.3 108.7bedded; contains glauconite; grades from bed below.

90_______ Chert: sandy, hard, light-gray (N 7), 7.4 116.1thick-bedded; contains glauconite; sand is very fine.

89 -___- Chert: silty, hard, light-gray (N 7), 14.7 130.8 280-47 1.7 thick-bedded; contains glauconite.

88-_____- Mudstone: gypsiferous, soft and me- .5 131.3 279-47 2.2 dium-hard, medium-gray (N 5), fissile.

87____-__ Chert: hard, medium-gray (N 5), thick- 3.6 134.9 bedded; contains glauconite; con tains skeletal apatite in lower part; contains gypsum in fractures; grades from bed below.

86_ ______ Chert: phosphatic, hard, medium- 1.2 136.1gray (N 5), thick-bedded; apatite is skeletal and finely pelletal; con tains flauconite. Fossil-collection numbers 9797, 9799.

Retort Phosphatic Shale Member of Phos phoria Formation:

Rt-85_ ______ Mudstone: medium-hard, light-gray 1.0 137.1(N 7) and medium-gray (N 5); grades from bed below.

84_ ______ Mudstone: hard, medium-light-gray 1.3 138.4(N 7) and light-brownish-gray (SYR 6/1), thin-bedded; grades from bed below.

83-_-_-_- Mudstone: medium-hard, grayish- 1.4 139.8 43-47 1.8 black (A 2), fissile.

82 _______ Phosphorite: muddy, medium-hard, .8 140.6 42-47 25.3weak-orange-pink (SYR 8/2), thick- bedded, medium pelletal.

81------- Mudstone: phosphatic, black (N 1), -7 141.3 41-47 13.7thin-bedded.

80-_---__ Phosphorite: muddy, medium-hard, .3 141.6 40-47 28.6 light-brown (5YR 6/4) and moderate- brown (5YR 4/4), thick bedded, finely pelletal.

79-----__ Mudstone: phosphatic, medium-hard, 1.2 142.8 moderate-brown (SYR 4/4), very finely pelletal; bed is brecciated; grades from bed below.

78---___- Phosphorite and mudstone, inter- 1.5 144.3 bedded: medium-hard moderate- brown (SYR 4/4) thin-bedded phos phorite inter bedded with medium- hard moderate-brown (5YR 4/4) thin-bedded phosphatic mudstone; apatite is finely to coarsely pelletal.

77----___ Mudstone: medium-hard, black (N 1), . 9 145. 2 fissile; gypsum coats fracture and bedding surfaces.

76--__-__ Phosporite: muddy, medium-hard, .6 145.8 light-brown (SYR 6/4), thin-bedded, very finely pelletal; grades from bed below.

75_--_-_- Mudstone: phosphatic, medium-hard, .5 146.3 35-47 10.1 53.8 light-brown (SYR 6/4) to moderate- brown (SYR 4/4), thin-bedded.

74_ ______ Mudstone: medium-hard, moderate- .4 146.7 34-47 4.8 71.5brown (SYR 4/4), very thick bedded.

Uranium

66. 7

30. 1

51. l

22. 2

39-47 17.0 45. 1

38-47 22. 1 32. 8

37-47 6. 1 45. 5

36-47 22. 2 32. 0

Radio- metric e\J

0.001

.0005

. 001

.0005

.001

.001

.003

Chemical U

0. 000

.000

.000

.000

.000

.000

.001

2.44

1. 17

.003

.002

.002

.007

.004

.008

.016

.007

004

010

006

. 41 . 004

.000

. 000

. 001

.009

.002

.007

.005

. 007

. 010

.004


Dalys Spur, Mont., lots 1222 and 1223 ContinuedChemical analyses (percent)

Bed

Rt-73_

72

70.

69-

68.

67_

66_

65_

64 _

63-

62_

61-

60-

59-

58.

57-

56.

55.

54.

Description

Retort Phosphatic Shale Member of Phos- phoria Formation Continued

Phosphorite: muddy, medium-hard,black (N 1), thick-bedded, very finelyto coarsely pelletal; contains 0.01 ftthick seam of gypsum in middle.

Mudstone: medium-hard, black (N 1),thin-bedded; contains 0.1 ft thickseam of gypsum at top; grades frombed below.

Phosphorite: crumbly, light-brown(5YR 6/4) to moderate-brown (SYR4/4), thin-bedded, very finely pelletal; grades vertically and laterallyinto mudstone lenses; gypsum coatsfractured surfaces.

Mudstone: medium-hard, black (N 1),thin-bedded; gypsum coats fractures;grades from bed below. Fossil-colln.No. 9796.

Mudstone: medium-hard, black {N 1),fissile and thin-bedded; contains gypsum in fractures; grades from bedbelow.

Mudstone: medium-hard, black (N 1),thin-bedded; grades from bed below.Fossil-colln. No. 9795.

Mudstone: medium-hard, black (N 1),fissile; grades from bed below. Fossil-colln. No. 9794.

Mudstone: hard, black (N 1), fissile andthin-bedded; grades from bed below.Fossil-colln. No. 9793.

Mudstone: medium-hard, black (N 1),fissile; grades from bed below. Fossil-colln. No. 9792.

Mudstone : hard, dark-gray (N 3) , thin-bedded; grades from bed below.

Mudstone : hard, dark-gray (N 3) , thin-bedded; grades from bed below.

Mudstone: hard, black (N 1), thin-bedded ; grades from bed below. Fossil-colln. No. 9791.

Mudstone: medium-hard, moderate-brown (5 YR 4/4) , thin-bedded ; gradesfrom bed kelow.

Mudstone : medium-hard, grayish- black(N 2), thin-bedded; grades from bedbelow. Fossil-colln. No. 9790.

Mudstone : medium-hard, grayish-black(N 2) , thin-bedded ; irregular contactwith bed below. Fossil-colln. No.9789.

Phosphorite: hard, dark-gray (A 3),thick-bedded; finely pelletal andnodular; irregular contact with bedbelow.

Mudstone: hard, black (N 1), thin-bedded; contains gypsum on fractured surfaces.

Phosphorite: hard, dark-gray (N 3),very thick bedded; medium pelletal.

Mudstone: medium- hard, dark-gray(N 3), fissile and thick-bedded; contains seams and lenses of gypsum infractures and on bedding surfaces;grades from bed below. Fossil colln.No. 9787.

Phosphorite: muddy, medium-hard,dark-gray (N 3), thin-bedded, veryfinely pelletal; contains gypsumseams in fractures.

Thick- Cumvla-ness tive thick-(Jeef) ness (feet)

Uranium

Acid in- Radio- Chemical Sample PzOs soluble F metric eV U

0. 4 147. 1 WRL-33-47 22. 4 23. 5

. 3 147. 4

. 3 147. 7

4. 0 151. 7

5. 0 156. 7

. 8 157. 5

2. 1 159. 6

1. 6 161. 2

2. 7 163. 9

1. 2 165. 1

1. 2 166. 3

1. 6 167. 9

. 8 168. 7

1. 7 170. 4

1. 2 171. 6

. 3 171. 9

. 8 172. 7

1. 2 173. 9

1. 4 175. 3

1. 7 177. 0

32-47 2. 9 55. 8

31-47 19. 0 33. 0

30-47 4. 2 42. 6

29-47 2. 9 49. 9

28-47 2. 7 61. 3

27-47 .6 65. 9

26-47 1. 6 67. 9

25-47 2. 0 63. 3

24-47 1. 6 65. 5

23-47 0. 6 63. 6

22-47 1.1 35. 0

21-47 1. 2 69. 4

20-47 1. 8 71. 5

19-47 2. 9 50. 2

0. 010 0. 008

. 003

.009 . 007

.003

.004

.003

. 002

. 003

.003

.002

. 002

. 002

.002

.002

.004

18-47 27. 4 19. 3 3. 8 . 007

17-47 4. 4 60. 6 .003

16-47 33. 1 6. 7 4. 1 . 007

15-47 6.8 52.3 ____ .005

14-47 22. fi 24. 62 __ .007

. 002

.005

.002

.007

.003

.005

Bed

STRATIGRAPHY AND PETROLOGY, PERMIAN ROCKS

Dalys Spur, Mont., lots 1222 and

Description

OF SOUTHWESTERN MONTANA

' Continued

411

Thick- Cumula-ness live thick-(feet) ness (feet)

Retort Phosphatic Shale Member of Phos-phoria Formation Continued

Rt-53.______ Dolomite: hard, olive-gray (5Y 4/1), .9 177.9thick-bedded.

52_______ Mudstone: phosphatic, medium-hard, .8 178.7grayish-black (N 2), thin-bedded; apatite is finely pelletal.

51__.___- Phosphorite: medium-hard, brownish- .3 179.0 black (10 YR 2/1), thick-bedded, very finely pelletal and nodular.

50. _ _ _ _ Mudstone: soft, light-brown (5 YR 6/4), . 2 179. 2 thin-bedded.

49______- Phosphorite: hard, light-brownish-gray .3 179.5(5YR 6/1), thin-bedded, very finely pelletal; grades from bed below.

48--__--_ Mudstone: hard, brownish-gray (5 YR .6 180.1 4/1), thin-bedded; grades from bed below.

47_-__-_- Phosphorite: hard, light-brownish-gray .4 180.5 (5YR 6/1), thin-bedded; very finely pelletal.

46. _-_-.- Phosphorite: muddy, medium-hard, 1.3 181.8 light-gray (N 7), thick-bedded, very finely pelletal; upper 0.3 ft is crumbly.

45.______ Mudstone: medium-hard, light-gray . 5 182. 3(N 7), thick-bedded; contains a few phosphorite nodules at center and at top.

44_______ Phosphorite: hard, medium-gray (N 5), . 2 182. 5"\thick-bedded, very finely pelletal.

43_____._ Mudstone: hard, light-olive-gray (5Y .3 182.8 5/2), thick-bedded.

42_______ Phosphorite: hard, medium-gray (N 5), . 6 183. 4thick-bedded, very finely pelletal.

41_._____ Mudstone: hard, light-olive-gray (5Y .4 183.8 5/2), thick-bedded.

40.______ Mudstone: medium-hard, light-olive- 1. 0 184. 8gray (5Y 6/1), thick-bedded; con tains a few phosphorite nodules 0.3 ft below top of bed.

39-______ Phosphorite: muddy, medium-hard, 1. 6 186. 4medium-gray (N 5), thin-bedded, very finely pelletal; contains thin gypsum seam 0.6 ft below top; grades from bed below.

38_______ Phosphorite: muddy, medium-hard, 1. 4 187. 8light-gray (N 6), finely pelletal; con tains several thin seams of gypsum.

37_______ Mudstone: medium-hard, light-brownish- .9 188.7gray (SYR 6/1), thin-bedded; con tains gypsum.

36_______ Mudstone: phosphatic, medium-hard, .8 189.5very light gray (N 8), thick-bedded.

35_._____ Mudstone: phosphatic, hard, medium- 1. 2 190. 7 light-gray (N 7), thin-bedded; may be sandy.

34_______ Phosphorite: sandy, hard, medium- 1. 1 191. S\gray (N 5), very thick bedded; con tains glauconite and skeletal apatite fragments; grades from bed below.

Franson Tongue of Park City Formation: F-33_______ Sandstone: phosphatic, hard, medium- 1. 1 192. 9

gray (N 5), fine-grained; contains glauconite and phosphatic skeletal fragments.

32_______ Sandstone: cherty, hard, light-gray (N 1. 6 194. 5"7), very thick bedded, fine-grained.

31_______ Chert: hard, light-gray (N 7), thick- 1.1 195.6bedded.

Chemkal analyses (percent)

Uranium

SampleAcid in- Radio- Chemical soluble F metric e~U U

WRL-13-47 3.9 18.6 ____ 0.001

12-47 10.0 49.1 _.-- .004

11-47 22. 8 21. 3 . 005 . 003

10-47 11.0 48. 3 .004

9-47 24. 4 24. 7 2. 48 .005 . 005

8-47 .2 68.3 __ .001 .000

7-47 14. 7 48. 2 1. 28 . 005 . 003

6-47 5. 3 71. 2 .68 . 002 . 003

5-47 17.2 36.9 _-__

4-47 20.3 27.5 _-__

3-47 8.8 62.1 _.__

2-47 3.3 75.8 ..__

1-47 13. 8 45. 9 1. 33

. 005 . 003

.005

. 004

. 003

. 005

. 003

. 003

. 007

.003

276-47 15. 1 56. 1 1. 39 . 003 . 003

275-47 3. 9 77. 2 . 001 . 001



Bed - Description

Franson Tongue of Park City Forma tion Continued

F-30-------- Sandstone: calcareous, hard, light-gray(N 7), very thick bedded, fine grained.

29---.---- Sandstone: hard, light-gray (AT 7),thick-bedded, fine-grained; grades from bed below.

28-___---_ Chert: hard, light-gray (N 7), thick- bedded.

27__------ Siltstone: cherty(?), light-gray (N 7),thick-bedded; grades from bed below.

26____--__ Sandstone: cherty(?), light-gray (N 7),thick-bedded, fine-grained; grades from bed below.

25________ Chert:sandy, hard, medium-gray (N5),very thick bedded.

24________ Sandstone: hard, light-gray (N 7), verythick bedded, fine-grained; grades from bed below.

23 ________ Sandstone: medium-hard, light-gray(N 7), very thick bedded, fine grained; contains chert nodules in upper 6.7 ft.

Rex Chert Member of Phosphoria Forma tion:

R-22________ Chert: sandy, medium-hard, very lightgray (AT 8), thick-bedded.

21________ Sandstone: medium-hard, light-gray(N 7),thick-bedded, very fineg-ained; contains glauconite and phosphatic skeletal fragments.

20________ Chert: hard; contains glauconite-_____19________ Sandstone: hard, medium-gray (N 6),

thick-bedded, fine-grained; contains glauconite.

Meade Peak Phosphatic Shale Member ofPhosphoria Formation:

M-18__-___- Siltstone: sandy(?), hard, light-gray (N 7), thin-bedded; uppermost 1.0 ft contains some very fine apatite pel lets.

17_ ______ Mudstone: hard, light-brownish-gray(5YR 6/1), thin-bedded.

16_______ Phosphorite: soft and crumbly, verylight gray (AT 8), thick-bedded, finely to coarsely pelletal.

l5-_____- Mudstone: medium-hard, light-olive- gray (5Y 6/1), thin-bedded. Fossil- colln. No. 9798.

14_______ Phosphorite: soft and crumbly, light- gray (N 7) and reddish-gray, thin- bedded; finely oolitic and pelletal; contains phosphatic skeletal frag ments.

Thick- Cumula-ness five thick-(feet) ness (feet) Sample

8. 7 204. 3 WRL-274-47

11.0 215.3 273-47

9. 2 258. 2

10. 0 268. 2

1. 0 269. 2

6. 0 275. 26. 1 281. 3

3. 1 284. 4


Uranium

Acid in- Radio- Chemical soluble F metric eV U

0. 8

1. 3

9.0

7. 2

7.3

2.8

7.4

224. 3

231. 5^1

238. 8 1

241. 6

249. 0

272-47

271-47

270-47

269-47

. 2

. 5

1. 3

2. 5

46.9 -___ 0.001 0.000

90.8 _--_ ------ _-----.

95.1 --__ .0005 .000

92.8 --__ ------ -------

91.3 .-_- ------ -------

78.2 _--_ .001 .000

268-47 5. 4 80. 0 0. 71 . 001 . 000

267-47 1. 9 87. 6

266-47 1. 1 92. 5

. 001 . 000

.001

265-47 6. 7 67. 0 .68 . 005

. 000

. 003

. 8

. 4

. 3

. 7

285.

285.

285.

286.

2

6

9

6

264-47

263-47

262-47

261-47

6.

35.

4.

36.

0

7

5

4

69.

6.

76.

5.

6 _.._

4 3.56

5 -_--

2 3. 57

. 003

.011

.003

. 009

.001

. 010

.001

. 008



413

Bed Description

Grandeur Tongue of Park City Formation: Gr-13_._____ Sandstone: medium-hard, yellowish-

gray (5Y 7/2), thick-bedded, fine grained.

12_ ______ Clay: soft, very light gray (N 8)11______- Sandstone: medium-hard, ligh

(N 7), thick-bedded, fine-gr grades from bed below.

10_______ Sandstone: cherty, medium-hard, verylight gray (N 8), thick-bedded; unit is brecciated.

9_---___ Siltstone: cherty, sandy, softdium-hard, grayish-yellow (5Y 8/4), thick-bedded.

8_______ Siltstone: soft to medium-hard, gray ish-yellow (5Y 8/4), thick-bedded.

7___-___ Siltstone: calcareous, sandy, sc medium-hard, grayish-yellow 8/4), thick-bedded; grades from bed below.

6_______ Sandstone: calcareous, silty, medium- hard, light-gray (N7), thick-bedded, very fine grained.

5__.____ Dolomite: medium-hard, verygray (N 8), aphanitic; contains nu merous black medium-gri lets (manganese-oxide?); grades from bed below.

4_______ Siltstone: sandy, medium-hard,lowish-gray (5Y 7/2), thin-bedded.

3_______ Dolomite: medium-hard,gray (5Y 7/2), very thick bedded; contains pellets similar to found in bed G-5.

2_______ Mudstone: soft, pinkish-gray,bedded.

!_______ Dolomite: hard, yellowish-gray7/2), very thick bedded. Underlain by sandstone of Quadrant Forma tion.


Thick- Cumula-ness tive thick-(feet) ness (feet) Sample

Uranium

Acid in- Radio- Chemical soluble F metric eU U

2. 4 289. 0 WRL-260-4 4. 4 84. 4 0. 001 0. 001

t-gray ained ;

, very ; unit

o me-7 8/4),

gray- led.Dft to

(5Ym bed

2.

1.

2.

1.

1.

8 5

4

0

0

2

dium- 3. 03dded,

light as nu- d pel- sfrom

yel- ded.owish-idded; those

thin-

(5Y

2.

3.

1.

6.

8

7

5

5

7

289. 292.

293.

295.

296.

297.

300.

303.

304.

8] 3 259-47

7 258-47

r

7

9257-47

9 256-47

7 255-47

4 254-47

307. 9 253-47

309.

316.

4 252-47

1 251-47

. 5 82.

.8 90.

. 6 80.

. 1 76.

. 2 18.

. 5 79.

. 0 2.

. 4 80.

.3 1.

0 ____

5 ____

0 ___.

6 ____

9 ---_

3 ___.

6 ____

6 ___.

9 ____

. 002

. 001

.002

.001

.0005

.002

.0005

. 002

.0005

. 000

. 000

. 000

. 000

.000

.000

.000

.000

.000

709-931

Big

She

ep C

anyo

n, M

ont.,

lot

s 12

24,

1225

, 12

26,

and

1227

[Per

mia

n ro

cks

mea

sure

d an

d sa

mpl

ed in

han

d tr

ench

es a

nd n

atur

al e

xpos

ures

on

east

lim

b of

Dix

on M

ount

ain

sync

line;

lot

122

4 m

easu

red

in N

EJ<

S W

J£ s

ec.

26; l

ot 1

225,

in

SE

^SW

Ji s

ec. 3

5; l

ot 1

226,

in

NE

^NW

V

sec.

35,

T.

13 S

., R

. 10

W.;

lot

1227

, in

N W

MN

WJ4

sec

. 11

, T.

14 S

., R

. 10

W.,

Bea

verh

ead

Cou

nty,

Mon

t. B

eds

stri

ke n

orth

wes

t an

d di

p 30

-40°

SW

. M

easu

red

by W

. R

. L

owel

l and

sam

pled

by

D.

A.

Bos

twic

k E

. T

. R

uppl

e, a

nd R

. L

. P

arke

r in

Aug

ust

1917

. Sa

mpl

es a

naly

zed

for

uran

ium

and

org

anic

mat

ter

by U

.S.

Geo

l. Su

rvey

, an

d fo

r ot

her

cons

titu

ents

by

U.S

. B

ur.

of M

ines

. L

OI,

los

s on

igni

tion]

Che

mic

al a

naly

ses

(per

cent

)

Bed

To

-23

2

231_

____

230_-_

_-

229-.

---

228-.

-.-

227_

.___

22

6_

--_

-

22

5--

__

-

224

_ _

223--

.--

22

2_

--_

-

22

1_

-__

-

220_--

--

219-.

---

218--

__-

21

7--

.-.

216_

___.

215_

_ _

214_

___.

213.-

__.

Cs-

21

2_

__

_.

211._

__.

210__-_

.2

09

__

_..

208_

___.

Des

crip

tion

Tos

i C

her

t M

embe

r of

Phosp

ho

ria

Fo

rma

ti

on:

Cher

t:

calc

areo

us,

silt

y,

har

d,

oliv

e-

gray

(5

Y

4/1)

. O

verl

ying

bed

s ar

e pro

bab

ly t

he

basa

l par

t of

the

Din

-w

oody

Form

atio

n.

Mud

ston

e:

cher

ty,

carb

onat

ic,

har

d,

oliv

e-gr

ay (

5Y 4

/1),

thin

-bed

ded

.S

imil

ar t

o b

ed T

o-23

1__

____

____

____

Sim

ilar

to b

ed T

o-2

31____

_ _

Sim

ilar

to b

ed T

o-23

1__

_-__

_ _.

_ _

Sim

ilar

to b

ed T

o-2

31.

____

____

__ _

Mud

ston

e:

carb

onat

ic,

mo

der

ate-

yel

lo

wis

h-br

own

(10Y

R

5/4)

, th

in-

bedd

ed.

Mud

ston

e:

carb

onat

ic,

med

ium

-har

d,

brow

nish

-gra

y (5

YR

4/

1),

thin

-be

dded

.C

her

t:

mu

dd

y,

dolo

mit

ic,

har

d,

me

diu

m-d

ark

-gra

y

(N 4

), t

hin

-bed

ded

.C

her

t:

mu

dd

y,

dolo

mit

ic,

har

d,

me

diu

m-g

ray (N

5),

thic

k-b

edded

.C

her

t:

carb

onat

ic,

har

d,

med

ium

-dar

k-g

ray (

N 4

), t

hic

k-b

edded

.C

her

t:

mud

dy,

har

d,

oliv

e- g

ray

(5Y

4/1)

, th

ick-b

edded

.C

her

t:

har

d,

oliv

e-gr

ay

(5Y

4/

1),

thic

k-b

edd

ed;

grad

es

from

under

ly

ing

cher

t.S

imil

ar t

o b

ed T

o-22

0_ _

____

____

____

Cher

t:

har

d,

oliv

e-gr

ay (

5Y

4/1

), t

hin

-be

dded

.D

olo

mit

e:

muddy,

har

d,

moder

ate-

yell

owis

h-br

own

(IO

YR

5/

4),

thic

k-

bedd

ed,

aph

anit

ic.

Cher

t:

har

d,

oliv

e-gr

ay (

5Y

3/2

), t

hin

-be

dded

.S

imil

ar t

o b

ed T

o-21

6__

____

____

____

. _

Cher

t:

har

d,

oliv

e-gr

ay (

5 Y

4/1

), t

hin

-bed

ded

.C

arbonat

e ro

ck:

har

d,

mo

der

ate-

yel

lo

wis

h-br

own

(1Q

YR

5/4

), v

ery

th

ick

bedd

ed,

aph

anit

ic.

Cher

ty s

hale

mem

ber

of

Phosp

hori

a F

orm

ati

on: Mudst

one:

h

ard

, ol

ive-

gray

(5

Y

4/1)

,th

in-b

edd

ed.

Sim

ilar

to b

ed C

s-21

2___

__ _

_ _

____

_S

imil

ar t

o b

ed C

s-21

2__-

_ __

_

___

Sim

ilar

to b

ed C

s-2 1

2 _

_

_ __

_S

imil

ar t

o b

ed C

s-2

12 _ _

.__

__

__

Thic

k-

Cum

ulat

ive

ness

th

ickn

ess

(feet

) (fe

et)

25.

0 25

. 0

3. 4. 5. 4. 4 1. 4. 5. 5. 4. 5. 1. 4 4. 4. 1. 1.

5 0 0 2 2 8 3 6 0 0 7 0 7 4 8 9 5 9 0

2. 2

5. 2. 2. 2.

0 2 5 7

28.5

32.5

37.5

41.

745.9

46.7

48.

0

52.6

57.6

62.

6

67

.3

72.

3

74.

078.4

79.2

84.

1

88.

690.5

91

.5

93.7

98.7

100.

910

3.4

106.

1

Sam

ple

Lot

122

4

WR

L-2

22-4

7

221-

4722

0-47

219-

4721

8-47

217-

47

216-

47

215-

47

214-

47

213-

47

212-

47

211-

47

210-

4720

9-47

208-

47

207-

47

206-

4720

5-47

204-

47

203-

47

202-

4720

1-47

200-

4719

9-47

P20

5

1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 2. 1. 1. 1. 1. 1. 1. 1.

5 3 3 8 2 9 9 2 6 0 2 5 4 2 5 3 6 3 5 5 4 5 9 4

Aci

d in

sol

ub

le

AljO

a Fe

jOa

78.

71.

74.

74.

75.

66.

75.

76.

80.

80.

80.

78.

85.

77. 3. 74.

75.

85. 1. 76.

78.

76.

75.

80.9

____

__

___

7 __

._

____

_6

____

__

___

6 __

__

____

_5

____

__

___

6 -_

-_

____

_

3 __

_-

____

_

1 __

__

---_

_

9 __

__

____

_

3 __

__

3 _-_

- _-_

--

9 -_

_-

____

_

0 --

_-

____

_8

_.__

__

___

0 __

_-

____

_

3 --

-_

____

_

5 __

._

____

_7

._--

__

___

4 __

__

____

_

4 __

_ __ -

7 __

__

____

_7

_--

--

---

5 ._

__

____

_4

_-__

_

__

Ura

nium

Rad

io

Org

anic

m

etri

c C

hem

ical

V

sOs

LO

I m

atte

r eV

U

O

H

O

__

__

_

f1

O

O K!__

___

____

__

____

0.0

005

____

__ _

_

_

__ _

- .0

01

____

____

- __

__

0.8

1

.001

____

_ _

_ __

._

_ ___

.00

05

__

____

___

____

_ _

__

.00

1--

_-_

--

-_

.54

.00

05

__

__

_-__

_ _.

__

____

__

.001

-___

. 000

5

____

_ __

__

.91

.0005

---_

. 00

05

____

_ __

__

____

__

. 00

05

__

_

____

_ __

__

____

__

.00

1

____

____

_ __

-_

__-_

_-

.0005

-_-_

____

_ __

__

____

__

.001

____

____

_ __

_-

____

__

.00

05

_-

__

____

_ __

__

2.0

8

.002

.002

____

_ __

__

____

__

.00

05

_

-.-

. 00

05

---_

____

_ __

__

____

__

.001

____

____

_ __

__

____

__

.001

___.

____

_ __

_.

3.2

9

.002

____

____

_ __

_-

____

__

.0005

____

_ __

__

____

__

.001

--.-

O S) h- 1

% O n W h- 1

^ H H h>>

O GO

---

M n ^ H Hj

H f O

207.

206.

20

5-

204.

20

3.

202.

201.

200.

199.

Rt-

198.

197.

196.

195.

194.

193.

192-

191.

190.

189.

188.

187.

186.

185.

184.

183.

182.

181.

180-

179.

178.

177.

176.

Mud

ston

e:

med

ium

-har

d,(5

74/1

), t

hin-

bedd

ed.

Sim

ilar

to

bed

Cs-

207_

____

____

____

Sim

ilar

to

bed

Cs-

207_

____

____

____

Sim

ilar

to

bed

Cs-

207_

____

____

____

Sim

ilar

to

be

d C

s-20

7;

grad

es

from

bed

belo

w.

Mud

ston

e:

med

ium

-har

d,

oliv

e-gr

ay(5

74

/1),

thi

n-be

dded

. S

imil

ar t

o be

d C

s-20

2___

____

____

__S

imil

ar t

o be

d C

s-2

02

__

__

__

__

__

_S

imil

ar t

o be

d C

s-20

2; g

rade

s fr

om b

ed

belo

w.

Fos

sil-

coll

n.

No.

99

13 f

rom

be

ds C

s-19

9 th

roug

h C

s-20

2.

Ret

ort

Pho

spha

tic

Sha

le M

embe

r of

Pho

s-

phor

ia F

orm

atio

n:M

udst

one:

sof

t, gr

ayis

h-bl

ack

(N 2

) to

dark

-gra

y (A

T 3)

, fi

ssile

. S

imil

ar t

o b

ed R

t-19

8___

____

____

__S

imil

ar t

o be

d R

t-198 _

____

____

____

Mud

ston

e:

ph

osp

hat

ic

carb

onat

ic,

med

ium

-har

d,

med

ium

-gra

y (N

5)

, ve

ry t

hick

bed

ded.

Car

bona

te

rock

: m

uddy

, so

ft,

dark

- gr

ay (

AT 3

).

Mud

ston

e:

soft

, da

rk-g

ray

(N

3),

fiss

ile.

Mud

ston

e:

med

ium

-har

d,

dark

-gra

y (N

3)

an

d br

owni

sh-b

lack

(1

0Y

R

2/1)

.P

hosp

hori

te:

med

ium

-har

d,

dark

-gra

y (N

3),

thi

n-be

dded

; no

dula

r in

bas

al

0.3

ft a

nd i

n up

per

0.3

ft.

Mud

ston

e:

med

ium

-har

d,

gray

ish-

bl

ack

(N 2

), th

in-b

edde

d.

Pho

spho

rite

m

ediu

m-h

ard

gray

ish-

bl

ack

(N

2),

thin

-bed

ded,

fi

nely

pe

llet

al.

Sim

ilar

to

bed

Rt-

190_

____

____

____

Pho

spho

rite

: m

uddy

, so

ft,

brow

nish

- gr

ay (

5Y

R

4/1)

, fi

ssile

, no

dula

r an

d fi

nely

pel

leta

l.M

udst

one:

ca

rbon

atic

, m

ediu

m-h

ard,

ol

ive-

gray

(5

7

3/2)

, th

in-b

edde

d;

grad

es f

rom

bed

bel

ow.

Mud

ston

e:

phos

phat

ic,

med

ium

-har

d,

brow

nish

-bla

ck

(WY

R

2/1)

, th

ick-

be

dded

apat

ite

is fi

nely

pel

leta

l; g

rade

s fr

om b

ed b

elow

. S

imil

ar t

o be

d R

t-18

6 __

____

____

__S

imil

ar t

o be

d R

t-18

5___

____

____

__S

imil

ar to

bed

Rt-

168;

gra

des

from

bed

belo

w.

Pho

spho

rite

: m

ediu

m-h

ard,

ol

ive-

gray

(5 7

3/2

), t

hick

-bed

ded;

fin

ely

pell

etal

.M

udst

one:

m

ediu

m-h

ard,

ol

ive-

gray

(57

3/2

), t

hick

-bed

ded.

P

hosp

hori

te:

med

ium

-har

d, o

live

-bla

ck

(5 7

2/1

), t

hick

-bed

ded,

fine

ly p

elle

tal.

Mud

ston

e: s

oft,

oliv

e-bl

ack

(5 7

2/1

), fi

ssile

. S

imil

ar t

o be

d R

t-17

9___

____

____

__M

udst

one:

ph

osph

atic

, m

ediu

m-h

ard,

pa

le-o

live

(5

75

/2);

bas

al 0

.4 f

t, t

hick

- be

dded

; up

per

0.2

ft f

issi

le.ol

ive-

gray

5.

0

111.

110

7-47

1.

2 78

. 4

5. 0

5.

0

5. 0

5.0

4. 2

5. 0

3

.3

5. 0

5.

0

1.3

116.

112

1. 1

126.

113

1. 1

5. 0

13

6. 1

140.

314

5. 3

148.

6

5. 0

15

3. 6

158.

616

3.6

164.

9

4. 1

16

9. 0

5. 0

17

4. 0

1. 2

175.

2

2. 5

17

7. 7

. 3

178.

0

. 2

178.

2

. 2

178.

41.

5

179.

9

106-

47

105-

47

104-

47

103-

47

1.6

1.6

97-4

7 96

-47

95-4

7

8.9

80.2

1. 3

77. 4

1. 3

80. 3

102-

47

1. 3

79. 4

101-

47

1. 4

82. 6

100-

47

1. 3

81.

199-47

3. 5

66.

1

98-47

5. 8

50. 3

5. 6

50

. 5

7. 8

46. 3

6. 8

40. 8

94-47

1. 8

19. 2

93-47

5. 7

36. 7

92-4

7 6. 8

38.

1

91-47

26. 8

12. 3

90-47

8. 8

49. 4

89-47

22.5

41

. 7

88-47

6. 9

56. 9

87-4

7 16. 7

23. 7

86-47

21. 7

13. 5

85-4

7 12

. 9

32. 3

. 10

. 06

1. 40

23. 01

6. 78

001

001

001

002

001

001

001

001

003

003

003

003

004

0005

004

005

006

003

005

001

000

002

001

003

001

003

003

001

5.29

004

004

003

002

002

001

Big

She

ep C

anyo

n, M

ont.,

lot

s 12

24,

1225

, 12

26,

and

12

27

Con

tinu

edC

hem

ical

ana

lyse

s (p

erce

nt)

Ura

nium

Bed

Rt-

175- --

---

-

174--

----

-

173--

----

-i 79

17l-

--___

_

170-.

----

-

169--

---.

-

168

165

164

_-__

_.

16

3--

.. _

_.

1 ^Q

1 ^f

i

Ret

ort

Pho

sph

phor

ia F

orm

D

olom

ite:

ol

ive-

bla

apha

niti

D

olom

ite:

5/

2) t

hic

Sim

ilar

to

Pho

spho

ri

brow

nis

bedd

ed,

Dol

omit

e:

gray

(N

2/

1),

thii

M

udst

one:

br

owni

s]

bedd

ed;

phos

pho

Dol

omit

e:

brow

nis]

be

dded

, D

olom

ite:

i is

h-gr

ay

apha

niti

ph

osph

o M

udst

one

med

ium

ve

ry t

hi

Car

bona

te

ligh

t-gr

a M

udst

one

med

ium

be

dded

. C

arbo

nate

gr

ay

(5

niti

c.

Mud

ston

e m

ediu

m

4),

thii

no

dule

s.

Car

bona

te

gray

(5

niti

c.

Mud

ston

e m

ediu

m

bedd

ed;

ish-

gray

M

udst

one

dark

-gn

Pho

spho

ri

gray

ish-

ve

ry f

in

Des

crip

tion

atic

Sha

le M

embe

r of

Pho

s-

atio

n C

onti

nued

ph

osph

atic

, m

ediu

m-h

ard,

ck

(5

7

2/1)

, th

ick-

bedd

ed,

c.

med

ium

-har

d, p

ale-

oliv

e (5

Y

k-be

dded

, ap

hani

tic.

be

d R

t-17

5 ---

----

----

-,e

: m

uddy

, m

ediu

m-h

ard,

i

gray

(5

Y 7

,4/1

), v

ery

thic

k fi

nely

pel

leta

l. m

uddy

, m

ediu

m-h

ard,

dar

k-

3) a

nd b

row

nish

-bla

ck (

10 Y

R

i-be

dded

. ca

lcar

eous

, m

ediu

m-h

ard,

i-

gray

(5

7 4

/1),

ver

y th

ick

cont

ains

som

e fi

nely

pel

leta

l ri

te l

ense

s,

mud

dy,

med

ium

-har

d,

i-gr

ay (

5Y

R 4

/1),

ver

y th

ick

apha

niti

c.

nudd

y, m

ediu

m-h

ard,

bro

wn-

(5

YR

4/ 1

) , ve

ry th

ick

bedd

ed,

c ; c

onta

ins

som

e fi

nely

pel

leta

l ri

te l

ense

s,

carb

onat

ic,

ph

osp

hat

ic,

-har

d,

gray

ish-

blac

k (N

2),

ck

bed

ded,

ro

ck:

argi

llac

eous

, ha

rd,

y (A

T 7)

, th

ick-

bedd

ed,

dolo

mit

ic,

ph

osp

hati

c,

-har

d, d

ark-

gray

(N

3) ,

th

in-

rock

: ha

rd,

ligh

t-br

owni

sh-

YR

6/1

), t

hin-

bedd

ed,

apha

-

dolo

mit

ic,

phosp

hati

c,

-har

d, m

ediu

m-d

ark-

gray

(N

i-

bedd

ed;

cont

ains

ap

atit

e

rock

: ha

rd,

ligh

t-br

owni

sh-

YR

6/1

), t

hick

bed

ded,

aph

a-

carb

onat

ic,

ph

osp

hat

ic,

-har

d, d

ark-

gray

(N

3),

thi

n-

cont

ains

apat

ite

nodu

les.

:

mud

dy,

hard

, li

ght-

brow

n-

(5Y

R 6

/1),

thi

ck-b

edde

d.

: do

lom

itic

, m

ediu

m-h

ard,

ly (

Ar3

), t

hin-

bedd

ed,

te:

calc

areo

us,

med

ium

-har

d,

blac

k (N

2)

, th

in-b

edde

d,

ely

pell

etal

and

nod

ular

.

Thic

k-

Cum

ulat

iv

ness

th

ickn

ess

(feet

) (fe

et) L

o

0. 3

18

7. 2

. 2

187.

4

. 2

187.

6

1. 7

18

9. 3

. 5

189.

8

1. 3

19

1. r

1. 6

192.

7

2. 9

19

5. 6

1. 3

19

6. 9

1. 8

19

8. 7

1. 2

199.

9

1. 6

20

1. 5

. 6

202.

1

. 7

202.

8

1. 4

204.

2

1. 2

20

5. 4

. 6

206.

0

1. 5

207.

5

9

Sam

ple

t 1224 C

onti

nued

WR

L-8

4-47

83-4

7

82-4

7

> 81

-47

80-4

7

79-4

7

78-4

7

77-4

7

76-4

7

75-4

7

74-4

7

73-4

7

72-4

7

71-4

7

70-4

7

P.O

s

5. 4

13.8

5. 1

14.9

4.9 8.5

5. 3

9. 1

6.6

10.0

3.8

9.2

4.0 7. 1

18.0

Add

inso

l

uble

A

lzO

a Fe

sOs

341

_.-

- --

---

33

.2

.-__

_-

-__

39.9

__

__

----

-

33.7

_-

-_

----

-

26.3

_--

- --

---

41

Q

15.2

_--

- --

---

46.0

--

._

----

-

18.3

_-

_-

--_

-

42

.6

--__

--

---

15.2

__

-_

----

-

46.1

_--

- --

---

22.6

--

--

----

-

50.6

.-

--

----

-

26

.5

_-_-

--

---

Rad

io

Org

anic

m

etri

c V

.Os

LO

I m

atte

r eV

__.-

_ __

__

5.48

0.

002

____

_ __

--

__

---.

.0

05

____

_ _.

__

_-_

--.

.002

____

_ __

__

8.33

.0

04

____

_--

. -_

.-__

.001

_.

_ __

____

.0

03

_ _

_.__

2.

31

. 001

___.

__

_-

____

__

.003

____

_ __

_.

_--

--_

.0

02

____

_ __

__

9.47

.0

02

____

_ __

__

----

--

.001

____

_ _--

. __

____

.0

03

____

_ __

__

3.79

.0

02

____

_ __

__

____

__

.003

-.__

_ _

_

.__-

__

.004

Che

mic

al

U 0.00

0

.002

. 000

.001

.000

.000

. 000

.001

.000

.001

.000

.001

.000

.000

.002

GEOLOGY OF

PERMIAN

ROCKS

IN

THE

WESTERN

PHOSPHATE FIELD


O O

Oo

§o

§ §o o

oo

oo

<Ni 5 *

(N

(N

00

i J CO

(N

1C

cc Its

co00

^H O

00 *'

t-05 1C

o>

*COCO

o10

o>id Ir-

OsI J

Ci"*' "*

10o

CO

£Ir-

id

CO

TjiCO

oCO

l^- !>

T T00 t-

-

I 7 oo 10

t-7co1C

CO<M'i itM

00tM*i I tM

(H 0)

HX!

S^ ^3

5^

W.fl

2 ° fl -^>3 w ^T3

11

.-? « -, , ' -I, S3 T3

^3 rt A?

fcn <£ S3 CO

T3 r°fe

T3 >-;T5 S3 v

X!T3iT3

/ s aS3 S3h,ft

,_;

II -1&§

| 5 'lS.-oa^s'sg .a"s

N 2Sft-°2 % 2^? S^^o^^l^ i

6 ..o ..i-a'S ro"Iril^i"""

Bed

D

escr

iptio

n

Ret

ort

Pho

spha

tic

Sha

le M

embe

r of

Pho

s-ph

oria

Form

atio

n C

onti

nu

edR

t-139_-_

--_

_

Pho

spho

rite

: m

uddy

, ca

rbon

atic

, m

e

dium

-har

d,

brow

nish

-bla

ck

(1Q

YR

2/

1),

thic

k-be

dded

, fi

nely

pe

llet

al

and

nodu

lar;

gra

des

from

bed

bel

ow.

138_

____

__

Pho

spho

rite

: m

uddy

, ca

rbon

atic

, m

e

dium

-har

d,

brow

nish

-bla

ck

(1Q

YR

2/

1),

thin

-bed

ded,

fi

nely

pe

llet

al

and

nodu

lar;

gra

des

from

bed

bel

ow.

137_

___

___

Pho

spho

rite

: m

uddy

, m

ediu

m-h

ard,

brow

nish

-bla

ck

(1Q

YR

2/

1),

thin

- be

dded

, fi

nely

pel

leta

l an

d no

dula

r;

grad

es f

rom

b.e

d be

low

.13

6 __

___-

- P

hosp

hori

te:

mud

dy,

med

ium

-har

d,

brow

nish

-bla

ck

(10Y

R

2/1)

, th

in-

bedd

ed,

fine

ly p

elle

tal

and

nodu

lar.

135.

___

___

Mud

ston

e: p

hosp

hati

c, c

arbo

nati

c, m

e

dium

-har

d,

dark

-gra

y (N

3)

, th

in-

bedd

ed;

apat

ite

is f

inel

y pe

llet

al.

134_

____

__

Car

bona

te

rock

: ha

rd,

med

ium

-dar

k-

gray

(N

4),

thi

ck-b

edde

d, a

phan

itic

.13

3_ _

___-

- M

udst

one:

pho

spha

tic,

car

bona

tic,

me

di

um-h

ard,

br

owni

sh-b

lack

(1

0YR

2/

1),

thic

k-be

dded

; ap

atit

e is

fin

ely

pell

etal

; be

d is

cru

mpl

ed.

Fra

nson

Ton

gue

of P

ark

Cit

y F

orm

atio

n:

F-1

32

. __

____

S

ands

tone

: ca

lcar

eous

, ph

osph

atic

,ha

rd,

brow

nish

-gra

y (5

YR

4/

1),

very

th

ick

bedd

ed,

fine

-gra

ined

; ap

atit

e is

ske

leta

l;

cont

ains

gla

uco-

ni

te;

grad

es t

o sa

ndy

skel

etal

pho

s

phor

ite

at

top.

F

ossi

l-co

lln.

N

o.

1858

2.

131

____

___

Lim

esto

ne:

med

ium

-har

d,

ligh

t-gr

ay(N

7),

ver

y th

ick

bedd

ed;

uppe

r 2.

3 ft

sk

elet

al,

low

er

8.0

ft

apha

niti

c.

Fos

sil-

coll

n. N

o. 9

914

and

9915

.13

0. _

____

_ S

ands

tone

: ca

lcar

eous

, m

ediu

m-h

ard

very

lig

ht g

ray

(N 8

), an

d ol

ive-

gray

(5

F

4/1)

, ve

ry

thic

k be

dded

, ve

ry

fine

gr

aine

d;

cont

ains

gl

auco

nite

.12

9 __

____

_ C

hert

': sa

ndy,

har

d, m

ediu

m-l

ight

-gra

y(N

7),

thi

ck-b

edde

d.12

8_-_

_--_

C

hert

: sa

ndy,

ha

rd,

ligh

t-gr

ay

(N 7

) an

d li

ght-

oliv

e-gr

ay

(5Y

6/1

),

thin

- be

dded

.12

7___

____

D

olom

ite:

che

rty,

har

d, b

row

nish

-gra

y(5

YR

4/1

), t

hick

-bed

ded,

ap

hani

tic.

126.

____

__

Dol

omit

e: c

hert

y, h

ard,

bro

wni

sh-g

ray

(5Y

R 4

/1),

thi

ck b

edde

d, a

phan

itic

.12

5_ _

____

_ M

udst

one:

do

lom

itic

, m

ediu

m-h

ard

pale

-bro

wn

(5Y

R 5

/2),

thi

n-be

dded

. F

ossi

l-co

lln.

N

o. 9

916

and

1858

1.

Thic

k-

Cum

ulat

ive

ness

th

ickn

ess

(feet

) (fe

et)

Sam

ple

?, a

nd 1

22

7 C

on

tinued

Che

mic

al a

naly

ses

(per

cent

)

P.O

s ub

leA

ljOs

Fe_O

3V

205

Org

anic

LO

T m

atte

r

Ura

nium

Rad

io

met

ric

Che

mic

al

eU

U

£-

1

i

00

Lot

122

4 C

onti

nu

ed

1. 3

22

6. 8

W

RL

-52-

47

14.

6 32

. 7

4 22

7. 2

0. 0

04

. 5

227.

7

. 6

228.

3

. 6

228.

9

. 8

229.

7

1. 8

23

1. 5

1. 7

23

3. 2

51-4

7 15

. 9

29.

19.

82

. 005

002

50-4

7 11

. 2

43.

9

49-4

7 .8

19

. 5

48-4

7 8.

8

42.

7

47-4

7 13

. 3

55.

4

12.4

7

.004

.001

.004

.005

001

000

003

004

Lot

122

5

10.

3 24

3. 5

19

8-47

1

.0

32.

6 .5

1.

101

26

. 5

8. 3

25

1. 8

7. 4

25

9. 2

9. 9

26

9. 1

11.

0 28

0. 1

7. 2

28

7. 3

5. 0

29

2. 3

197-

47

1. 0

73

. 1

3. 5

2

.2

196-

47

. 7

73.

1 3.

5

2. 5

195-

47

. 5

75.

1 4.

3

3. 7

194-

47

. 5

63.2

1.

3

5. 1

193-

47

. 3

62. 3

3.2

2.6

192-

47

1. 1

59. 0

6. 2

2. 4

.01

01 01

8.4

9.8

8.0

01

12.

1

01

13. 8

01

14.

1

0005

0005

0005

0005

0005

001

002

3 H

JB

H

W W

3 ^ W o JB *d I H 3 H g

124.

123.

122.

121.

120.

118.

117.

116-

115.

114.

113.

112.

111.

110-

109.

108-

107.

106.

10

5-

Car

bona

te r

ock:

che

rty,

har

d, m

ediu

m-

gray

(N

5)

, ve

ry

thic

k be

dded

, gr

anul

ar;

grad

es

from

be

d be

low

. F

ossi

l-co

lln.

No.

991

7.L

imes

tone

: sa

ndy,

ha

rd,

ligh

t-

brow

nish

-gra

y (5

YR

6/1

), v

ery

thic

k be

dded

, sk

elet

al;

cont

ains

gla

ucon

ite.

F

ossi

l-co

lln.

No.

991

8.M

udst

one:

ca

lcar

eous

, ha

rd,

med

ium

- gr

ay

(N

5),

thin

-bed

ded;

co

ntai

ns

glau

coni

te.

Fos

sil-

coll

n. N

. 99

18.

San

dsto

ne:

dolo

mit

ic,

very

fin

e gr

aine

d;

cont

ains

gla

ucon

ite.

Dol

omit

e:

hard

, ye

llow

ish-

gray

(5

F

7/2)

, ve

ry

thic

k be

dded

, ap

hani

tic;

gr

ades

fro

m b

ed b

elow

.D

olom

ite:

san

dy,

hard

, ye

llow

ish-

gray

(5

F

7/2)

, ve

ry

thic

k be

dded

, ap

hani

tic.

San

dsto

ne:

hard

, ye

llow

ish-

gray

(5

F

7/2)

, ve

ry t

hick

bed

ded,

fin

e-gr

aine

d;

grad

es f

rom

bed

bel

ow.

Dol

omit

e:

sand

y,

hard

, li

ght-

gray

(A

T"

7),

thic

k-be

dded

, ap

hani

tic;

sa

nd

grai

ns a

re u

neve

nly

dist

ribu

ted.

Dol

omit

e:

sand

y,

hard

, m

ediu

m-g

ray

(N 5

), v

ery

thic

k be

dded

, ap

hani

tic;

sa

nd i

s un

even

ly d

istr

ibut

ed.

San

dsto

ne:

dolo

mit

ic,

hard

, m

ediu

m-

ligh

t-gr

ay (

N 7

), v

ery

thic

k be

dded

, fi

ne-g

rain

ed;

dolo

mit

e no

dule

s ar

e ir

re

gula

rly

dist

ribu

ted

thro

ugh

bed.

San

dsto

ne:

dolo

mit

ic,

hard

, m

ediu

m-

ligh

t-gr

ay (

N 7

), v

ery

thic

k be

dded

.D

olom

ite:

sa

ndy,

har

d, m

ediu

m-l

ight

- gr

ay (

N 7

), v

ery

thic

k be

dded

.L

imes

tone

: ha

rd,

med

ium

-gra

y (N

7),

ve

ry

thic

k be

dded

, gr

anul

ar;

cher

t no

dule

s ir

regu

larl

y di

stri

bute

d in

be

d.

Fos

sil-

coll

n. N

o. 9

919.

Car

bona

te

rock

: ch

erty

, ha

rd,

ligh

t-

brow

nish

-gra

y (5

YR

6/1

), v

ery

thic

k be

dded

; ge

odes

as

muc

h as

0.2

ft

in

diam

eter

lin

ed b

y ca

lcit

e an

d qu

artz

cr

ysta

ls a

re i

rreg

ular

ly d

istr

ibut

ed i

n be

d.

Fos

sil-

coll

n. N

o. 9

919.

San

dsto

ne:

dolo

mit

ic,

hard

, li

ght-

br

owni

sh-g

ray

(5Y

R 6

/1),

ver

y th

ick

bedd

ed,

fine

-gra

ined

; co

ntai

ns g

lau

co

nite

; ca

lcit

e ge

odes

as

m

uch

as

0.15

ft

in

di

amet

er

are

irre

gula

rly

dist

ribu

ted

in b

ed.

Car

bona

te r

ock:

sa

ndy,

har

d, m

ediu

m-

gray

(N

5),

thi

ck-b

edde

d, a

phan

itic

; co

ntai

ns g

lauc

onit

e.S

ands

tone

: do

lom

itic

, ha

rd,

med

ium

- li

ght-

gray

(N

7),

ver

y th

ick

bedd

ed,

fine

-gra

ined

.D

olom

ite:

sa

ndy,

har

d, m

ediu

m-g

ray

(N 7

), v

ery

thic

k be

dded

, ap

hani

tic.

Sim

ilar

to

bed

F-1

08__

____

____

____

_D

olom

ite:

sa

ndy,

har

d, m

ediu

m-l

ight

- gr

ay (

N 7

), t

hick

-bed

ded,

aph

anit

ic;

sand

irr

egul

arly

dis

trib

uted

in

bed.

4. 4

29

6. 7

4. 3

30

1. 0

3. 1

30

4. 1

1. 0

30

5. 1

2. 2

30

7. 3

4. 0

31

1. 3

3. 8

31

5. 1

2. 5

31

7. 6

2. 7

32

0. 3

5. 8

32

6. 1

2. 0

32

8. 1

1

5.3

33

3.41

7. 8

34

1. 2

3. 7

34

4. 9

1. 4

34

6. 3

4. 5

35

0. 8

8. 5

35

9.

2. 0

36

1. 3

1

1. 8

36

3. i

j2.

4

365.

5

191-

47

. 5

52.

9 .3

3.

5

.01

17.

6

190-

47

. 4

43.2

4.

1

1. 7

.0

1

22.

8

189-

47

. 6

62.

7 1.

1

2.7

.0

1

14.

5

188-

47

. 7

36.

0 .5

1.

1

.01

27.4

187-

47

.6

51.

3 .6

1.

6

.01

10.

9

186-

47

. 8

44. 6

.6

1. 7

.01

23. 2

185-

47

. 6

20. 5

.8

1. 2

.01

35. 0

184-

47

1. 8

58. 6

.2

1. 3

.01

16.

1

183-

47

. 8

37. 0

.7

1. 6

.01

26. 3

182-

47

. 3

43.

1 .5

2. 6

.01

22. 2

181-

47

. 3

63. 8

1. 3

3.2

.02

13. 5

180-

47

. 8

47.4

.6

2.04

.02

21. 5

179-

47

. 7

40. 6

.6

1. 6

.02

25. 4

178-

47

. 7

55. 4

.2

1. 9

.02

18. 5

177-

47

.6

21. 3

.9

1. 2

.01

34. 5

.0005

.0005

. 000

5

.0005

.0005

.000

5

.001

.000

5

.0005

.0005

.0005

.0005

.0005

.001

.0005

Big Sheep Canyon,

Mont

., l

ots 1224,

1225

, 1226, an

d 1227 Con

tinued

Bed

Des

crip

tion

Thic

k-

Cum

ulat

ive

ness

th

ickn

ess

(fee

t)

(fee

t)Sa

mpl

e

Che

mic

al a

naly

ses

(per

cent

)

Aci

d in

sol-

Pa

Os

uble

A

UO

3Fe

zOs

V20

5O

rgan

ic

LOT

mat

ter

Ura

nium

Rad

io

met

ric

Che

mic

al

eV

U

to O

Lot

. 122

5 C

onti

nu

ed

F-1

04__

____

10^

1O9

10

1--

----

R-1

00

-- _

.

QQ

no

97

QC

Q4

Q3

GO 91 QO

CO 87-.

--..

86--

-__-

85 84_-_

___

Fra

nso

n

To

ng

ue

of

Par

k

Cit

y

Fo

rma

ti

on

C

onti

nued

S

and

sto

ne:

dolo

mit

ic,

har

d,

med

ium

-li

gh

t-g

ray

(N

7),

ver

y t

hic

k b

edd

ed,

fin

e-g

rain

ed.

Do

lom

ite:

ch

erty

, sa

nd

y,

har

d,

med

ium

-li

gh

t-g

ray

(N

7),

ver

y t

hic

k b

edded

. D

olo

mit

e:

har

d,

med

ium

-lig

ht-

gra

y(N

7),

v

ery

th

ick

bed

ded

, g

ran

ula

r.

Fo

ssil

-co

lln

. N

o. 9

920.

S

and

sto

ne:

h

ard

, m

ediu

m-l

ight-

gra

v(N

7)

, ver

y

thic

k

bed

ded

; d

olo

- m

itie

in

upper

3.

0 ft

. R

ex

Ch

ert

Mem

ber

of

Phosp

hori

a F

orm

a

tion:

Cher

t:

sandv,

har

d,

med

ium

-gra

y(N

5)

, v

ery

th

ick

b

edded

; gra

des

fr

om

be

d be

low

. C

her

t:

har

d,

med

ium

-lig

ht-

gra

v (N

7),

thic

k-b

edded

; g

rad

es f

rom

bed

bel

ow

.

gra

vis

h -b

lack

(N

2),

th

in -b

edd

ed.

Sim

ilar

to

bed

R-9

8--

- __

_ __

__

Sim

ilar

to b

ed R

-98

- __._

_______--

__

Sim

ilar

to

bed

R-9

8-

________

Sim

ilar

to

bed

R-9

8__-_

__

__

--_

__

-_-

Sim

ilar

to b

ed R

-98

__

___

____

___

_.._

gra

yis

h-b

lack

(N

2)

, th

in-b

edd

ed;

gra

des

fr

om

bed

b

elow

; m

udst

one

par

tin

gs

0.05

ft

thic

k o

ccur

1.0,

1.

5,

and 3

.0 f

t ab

ove

bas

e.

Mudst

one:

m

ediu

m-h

ard

, gra

yis

h-

bla

ck

(N 2

),

fiss

ile.

Cher

t:

bri

ttle

, gra

yis

h-b

lack

(N

2)

,th

in-b

edd

ed.

Mudst

one:

bri

ttle

, gra

vis

h-b

lack

(N

2),

thin

-bed

ded

.

med

ium

-gra

y

(N

5),

thic

k-b

edded

; gra

des

fr

om

bed

bel

ow

. D

olo

mit

e:

oli

ve-

gra

v

(5T

3/2

),

thic

k-

bed

ded

, ap

han

itic

; phosp

hat

ic

nea

r to

p.

thic

k -b

edded

.

gra

y

(N

3),

thic

k-b

edded

; co

nta

ins

apati

te

no

du

les

and

skel

etal

fr

ag

men

ts i

n b

asal

0.2

5 ft

. F

oss

il-c

oll

n.

No

. 99

21

5.4 1.3

6. 2

9. 5

4. 2

2. 0

3.2

5.0

5. 0

5. 0

5. 0

5. 0

5. 0

4. 0 .5 . 9

1. 5 . 6

1 S

2.3

370.

9

372.

2

378.

4

387.

9

392.

1

394.

1

397.

3

402.

340

7.3

412.

341

7. 3

422.

342

7.3

431.

3

431.

81

432.

7

434.

2

434.

8

435.

6

437.

4

439

7

WR

L-1

76-4

7

175-

47

174-

47

173-

47

172-

47

171-

47

170-

47

169-

4716

8-47

167-

4716

6-47

165-

4716

4-47

163-

47

162-

47

161-

47

160-

47

159-

47

158-

47

157-

47

1. 5 . 2 1.

9 1.4 . 5 .3 . 4 . 3 .4 . 5 . 4 .5 . 4 . 5 1.

0 1. 4 .4 7

.5 3.2

11.7

62.2

9. 1

10.4

67.2

94.3

92.

8

88.

1

89.4

85.

979

. 7

78.

277

. 1

63.

489

. 7

79

9

74.3

22.

8

27.3

68.

7

43.

0

0.4 . 5 .3 . 6 .3 1. 0 1.3

1. 1

1. 6 1. 9

2. 1

1.7

1. 8

2.0

4.7 6.4 1.2

2.2 6. 8

1.8

0.9 1.

1 . 7 1.7

2. 9

2. 9

4.7 2. 9

4. 4

4. 9

4. 8

4.7

4. 0

3.2 3. 1

2. 7 . 8 1. 5

3. 1

1.7

0. 0

2

. 01

. 01

. 01

. 01

. 01

. 02

. 01

. 02

. 01

.01

. 02

. 01

. 02

. 01

.03

. 02

. 02

.04

.02

14.7

40.

7

37.

5

12.

4 .3 1. 0

2. 2

2. 6

3.4 5. 7

6. 9

7.2

13.

92.2 8.2 9.7

35.

1

24.9 9. 6

11.4

-__-

__

0.00

05

_-__

____

__

.000

5 __

__

____

__

.001

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____

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5 _-.

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005

-___

____

__

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...

____

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005

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____

____

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Sim

ilar

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ed G

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_ __

____

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Sim

ilar

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ed G

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____

____

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imil

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pal

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ish

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0R

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thin

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ded

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imil

ar t

o b

ed G

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____

____

____

____

Sim

ilar

to b

ed G

-41

____

____

____

____

Sim

ilar

to b

ed G

-41_

___

____

____

____

Sim

ilar

to

bed

G-4

1 _

__

.-_

__

--._

__

__

Sim

ilar

to b

ed G

-41

____

____

____

____

Sim

ilar

to b

ed G

-41;

gra

des

from

bed

be

low

.M

ud

ston

e:

dolo

mit

ic,

moder

ate-

red

di

sh-b

row

n (1

0R

4/

6),

ver

y

thic

k

bed

ded

; co

nta

ins

poor

ly

form

ed

cros

s-be

ddin

g.M

ud

ston

e:

dolo

mit

ic,

med

ium

-har

d,

dusk

y-ye

llow

(5Y

6/4

), t

hin

-bed

ded

.M

ud

ston

e:

dolo

mit

ic,

med

ium

-har

d,

mod

erat

e-ye

llow

ish-

brow

n (1

0 K

B

5/4)

, th

ick-b

edded

.S

andst

one:

do

lom

itic

, m

ediu

m-h

ard,

mode

rate

-yel

low

ish-

bro

wn

(1

0 K

B

5/4)

, th

in-b

edded

.S

imil

ar t

o b

ed G

-31-

____

____

____

___

Dol

omit

e: c

her

ty,

sand

y, h

ard

, ye

llow

is

h-g

ray (

5F

7/2

), t

hin

-bed

ded

, ap

ha-

n

itic

; sa

nd i

s ve

ry f

ine.

Dol

omit

e:

sand

y,

har

d,

wea

k-ye

llow

is

h-or

ange

(10

F.f

i 8/

4),

thic

k-b

edded

.C

her

t:

bri

ttle

, m

ediu

m-g

ray

(N

5)

, th

ick-b

edded

.D

olom

ite:

ch

erty

, b

ritt

le,

pale

-oli

ve

(5F

5/2

), t

hic

k-b

edded

, ap

han

itic

.D

olo

mit

e an

d c

her

t, i

nte

rbed

ded

: har

d

lig

ht-

bro

wn

ish

-gra

y (

5 K

B 6

/1)

thic

k-

bed

ded

ap

han

itic

do

lom

ite

inte

r-

bed

ded

w

ith

har

d

pale

-oli

ve

(5F

5/

2) a

nd

dusk

y-g

reen

(5G

3/2

) th

ick

- bed

ded

ch

ert;

irr

egu

lar

conta

ct w

ith

bed

belo

w.

Dol

omit

e:

har

d,

oliv

e-gr

ay

(5Y

4/

1),

thic

k-b

edded

, ap

han

itic

.

San

dst

one:

do

lom

itic

, har

d,

ver

y l

igh

t gra

y

(N

8)

and

light-

gra

y

(N

7);

grad

es f

rom

bed

bel

ow.

San

dsto

ne:

har

d,

light-

gra

y (

N 7

), v

ery

thic

k b

edded

; gr

ades

fro

m b

ed b

elow

.D

olom

ite:

har

d,

light-

gra

y (

N 7

), v

ery

th

ick b

edd

ed;

grad

es f

rom

bed

bel

ow.

Dol

omit

e: h

ard

, w

eak-

yell

owis

h-or

ange

(2

.5F

8/4

), t

hic

k-b

edded

, ap

han

itic

; sa

ndy i

n m

iddl

e p

art.

Dol

omit

e: h

ard,

pin

kis

h-g

ray (

5R

8/1

),

thic

k-b

edded

; gr

ades

fro

m b

ed b

elow

.D

olom

ite:

h

ard

, v

ery

lig

ht

gra

y

(N 8

) an

d m

ediu

m-l

ight-

gra

y (

N 7

), t

hic

k-

bed

ded

, ap

han

itic

; co

nta

ins

cher

t no

dule

s; g

rade

s fr

om b

ed b

elow

.

5.0

5.

0

5.0

5.

0

2. 5

3.7

5. 0

5.

0

5.0

5

.0

5. 0

5.0

4. 5

2. 8

1. 8

1. 8 .4

1.

9

2. 4

1. 0

2. 6

3. 5

534.

7

539.

7

544.7

54

9. 7

55

2. 2

555.

9

560.

9

565.

9

570.

9

575.

9

580.

9

585.

9

590.4

593.

2

595.

G\

596.

8f

597.

2\

599.

1J

601.

5

602.

5

605.

1

608.6

1. 8

11. 2

8. 0

7. 7

25. 6

5.8

122-

47

121-

47

120-

47

119-

47

118-

47

117-

47

116-

47

115-

47

114-

47

113-

47

112-

47

111-

47

1. 3

72.

11. 3

71. 4

70. 9

. 1

. 1

77. 9

.1

73. 2

. 1

1.3 . 1

. 1

1.4

1. 2

109-

47

108-47

250-

47

5. 6

616. 0

627. 2

635. 2

642. 9

668. 5

674. 3

68.9

65. 5

65.4

65. 6

65. 0

58. 6

110-

47

1. 2

69. 3

.2

65. 2

.3

70. 2

.5

48.

1

249-

47

.3

48. 4

248-

47

31. 4

12. 0

247-

47

.5

34.

1

246-

47

.3

29.

1

610.

4

24

5-4

7

. 1

Lot 1

227

244-

47

.0

48.

4

243-

47

.1

68.

3

242-

47

.1

28.

0

241-

47

1. 3

19

. 9

240-

47

.4

55.

1

.002

.002

. 00

2.0

01

.001

. 002

. 00

2. 0

02.0

02

.001

.002

.002

. 001

.002

.001

.001

.001

. 00

8

. 001

. 001

. 000

5

.0005

.001

.001

.0005

. 001

.007

to CO


-d0>

fl

OO

'a 8<sto" ®4

ea 2

10 10CO O Oo o o000

IQ iQ 1000 Oo o o00 O

-*0>CO

-*00

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CD rJH

rJH ^

CO C^to to

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1Co oo

1Co oo

l>00

PQ

r i^»

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CO§

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86

ISQ

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P


Sheep Creek, Mont., lot 1234

insoluble by U.S. Bur. of Mines and for all other constituents by U.S. Geol. Survey. LOI, Loss on ignition]

Bed Description

Dinwoody Formation, basal bed:

D-137___ Mudstone: dolomitic,soft, grayish-yellow(5Y 8/4), thin-bedded.

Intertonguing upper memberof Shedhorn Sandstone andTosi Chert Member ofPhosphoria Formation:

Us-136__-_ Sandstone: medium-hard, weak-yellowish-orange (10 YR 7/4), thick- bedded, fine-grained; contains glauconite; grades from bed below. Fossil-colln. Nos. 10823 and 18575.

To-135____ Mudstone and chert, interbedded: medium- hard very pale orange (10 YR 8/2) thick-bed ded cherty mudstone containing interbeds and lenses ranging from 0.05 to 0.9 ft in thick ness of hard light-gray (N 7) thick-bedded muddy chert; contains glauconite.

Us-134-___ Sandstone- hard, cherty, very pale orange (10F.R 8/1), thick - bedded, fine-grained; contains glauconite.

To-133_-__ Chert: Brittle, light-gray (N 7), thick-bedded; contains glauconite.

Us-132____ Sandstone: cherty, me dium-hard, brownish- gray (5YR 4/1), thick- bedded; fine-grained; contains glauconite.

131____ Sandstone: cherty, me dium-hard, brownish- gray (5YR 4/1), very thick bedded, fine grained; contains glau conite; grades from bed below.

130____ Sandstone: medium-hard, brownish - gray (5 YR 4/1), thick-bedded, fine-grained; contains glauconite and irregu lar discontinuous lenses and laminae of me dium-gray sandstone.

129____ Sandstone: medium-hard, brdwnish-gray (5YR 4/1), thick-bedded,fine grained; contains many lenses and interbeds of hard medium gray (N 7), thick-bedded cherty sandstone; con tains glauconite; grades from bed below. Fos sil-colln. No. 10822.

See footnotes at end of table.


Uranium


5.4

SampleAdd in soluble Al»Oj FesOs LOI

Organic matter

Radio- metric

eUChemical

U

DAB-80 1.0 71.4 8.1 4.0 10.0 _____ 0.0005 0.001

79 1. 7 87. 9 2. 5 4. 6 1. 5 . 0005 . 000

22. 2 28. 0 LAT-78 1. 6 87. 3 5. 1 3. 0 2. 3 . 0005 . 000

1. 1

1.0

1. 6

28. 6)

29. 7

30. 7

32. 3

5. 1 37. 4

45. 5

2 77 2. 1 8. 9 4. 4 3. 4 1. 8 . 0005 . 001

76 1.7 88.6 2.3 3.5 1.5 _____ .0005 .001


Bed Description

Intertonguing upper member of Shedhorn Sandstone and Tosi Chert Member of Phosphoria Formation Continued

Us-128____ Sandstone: hard, gray ish-brown (WYR 4/2), very thick bedded, fine-grained; contains glauconite.

To-127____ Chert: medium-hard grayish-brown (WYR 4/2) thin-bedded chert interbedded with brit tle medium-light-gray (N 7), thick-bedded chert; bedding surfaces are undulant.

Us-126____ Sandstone: hard grayish- brown (WYR 4/2), thick-bedded, very fine grained; contains (20 percent) lenses ranging from 0.2 to 0.5 ft in thickness of hard mod erate-brown cherty sandstone; contains glauconite.

To-125_ _ _ _ Chert: medium-hard very pale brown (WYR 7/2) thick-bedded chert in terbedded with hard light-gray (N 8) thin- bedded chert; grades from bed below.

Us-124 _ _ _ _ Sandstone: medium-hard, moderate-yellowish- brown (WYR 5/4), thin-bedded, very fine grained; contains (20 percent) lenses of hard brownish-gray (WYR 4/2) cherty sandstone; contains glauconite; grades from bed below.

123____ Sandstone: cherty, hard, brownish-gray (WYR 4/2), thick-bedded, very fine grained; con tains glauconite.

122_ ___ Sandstone: medium-hard, grayish-yellow (5F 8/4) to d a r k-y e 11 o w i s h- orange (WYR 6/6), thick-bedded, very fine grained; contains (30 percent) lenses of brit tle moderate-brown (5F#3/4) cherty sand stone; contains glau conite.

121._._ Similar to bed Us-123.._ 120_... Similar to bed Us-122-.

Sheep Creek Mont., lot 1234 ContinuedChemical analyses (percent)

Uranium


Acid in- PsO 5 soluble AlsOa

Organic LOI matter

Radio- metric Chemical

eU U

1. 2

5.9

46.7

52. 6

7.9 60. 5

ERC-75 2.4 86.9 2.1 3.9 1.0 .-_-. 0.0005 0.001

18.7 79. 2 74 2. 6 88. 1 2. 9 2. 8 1. 3 . 0005 . 000

11.8 91.0

1. 0 92.0

6. 5 98. 5

. 5 2. 9

99.0101. 9

73 2. 7 87. 0 1. 0 4. 0 1. 0 0005 . 001

DAB-72 3. 3 2. 2 3. 2 1. 2 0005 . 001


Sheep Creek, Mont., lot 1234- Continued

Bed Description

Intertonguing upper member of Shedhorn Sandstone and Tosi Chert Member of Phosphoria Formation Continued

To-119____ Chert: muddy, mottled light-gray (N 8) and moderate-yellowish- brown (WYR 5/4), thin-bedded.

118____ Chert: muddy, medium- hard, mottled light- gray (N 8) and strong- yello wish-brown (IOYR 5/8), thick- bedded.

Us-117____ Sandstone: cherty, me dium-hard, moderate- yellow (5Y 7/6), thick- bedded, very fine grained; contains glauconite; nearly half of the bed consists of ir regular lenses of hard, medium-light-gray (N 7), cherty sandstone.

116____ Sandstone: phosphatic, medium-hard, yellow ish-brown (1QYR 5/4), thick-bedded; apatite is medium pelletal.

Retort Phosphatic Shale Member of Phosphoria For mation :

Rt-115____ Mudstone: phosphatic, soft, laminated gray ish-brown (10 YR 4/2) and brownish-gray (SYR 4/1), thin- bedded; apatite is very finely pelletal.

114____ Mudstone: soft, lami nated brownish-black (5YR 2/1) and moder ate-brown (5YR 4/4), thin-bedded. Fossil- colln. Nos. 10909 and 10820.

113____ Mudstone: phosphatic, soft, laminated brown ish-black (5YR 2/1) and moderate-brown (SYR 4/4), thin-bed ded; apatite occurs as fine-grained pellets concentrated in the brownish-black lami nae. Fossil-colln. Nos. 10908 and 10819.

H2____ Mudstone: soft, brown ish-black (IQYR 2/2), thin-bedded; contains (10 percent) moderate- brown (5YR 4/4) mudstone laminae. Fossil- colln. Nos. 10907 and 10818.

111____ Mudstone: soft, brown ish-black (5YR 2/1), thin-bedded. Fossil- colln. No. 10906.


Uranium

Thick- Cumulativeness thickness(feet) (feet) Sample P206

Acid in soluble AhOa FejO 3 LOI

Organic matter

Radio- metric

eUChemical

U

1. 8 103. 7

9. 5 113. 2

3. 4 116. 6

DAB-71 1.6 88.3 4.8 2.3 2.8 _____ 0.0005 0.001

70 3. 0 87. 9 1. 0 3. 2 . 0005 . 001

8 117. 4 69 17. 2 51. 1 2. 2 1. 5 . 006 . 003

9 118. 3 VEM-1 16. 2 43. 6 7. 4 3. 6 8. 0 .007

1. 3 119. 6

2. 3 121. 9

7. 4 64. 6 9. 2 2. 4 9. 7 . 004

.004

. 001

3 12. 5 51. 9 8. 7 2. 3 10. 0 3. 30 004 . 004

1. 3 123. 2 1. 7 79. 0 11. 2 1. 9 9. 3 . 003 .001

2. 2 125. 4 JES-5 3. 2 70. 4 9. 9 4. 3 13. 4 .002 .002


Sheep Creek, Mont., lot 1234 ContinuedChemical analyses (percent)

429

Bed Description

Retort Phosphatic Shale Member of Phpsphoria For mation Continued

Rt-110_- Mudstone: soft, lami nated brownish-black (IOYR 2/2) and mod erate-brown (5YRB/4), thin-bedded; grades from bed below. Fos-

.sil-colln. No. 10905.109.--- Mudstone: phosphatic,

soft, laminated moder ate-yellowish-brown (10 YR 5/4) and dusky- yellowish-brown (10F.R 2/2), thin-bedded; apa tite is finely pelletal; grades from bed below. Fossil-colln. No. 10904.

108.--- Mudstone: phosphatic, medium-hard, grayish- black (N 2), thin-bed ded; contains a few lenses averaging 1 mm thick of moderate-yel lowish-brown (ioy.R 5/4) pelletal phospho rite.

107.--- Phosphorite: muddy, crumbly, erayish- brown (IOYR 4/2), thick-bedded, medium pelletal and nodular; nodules are approxi mately 10 mm in di ameter; irregular con tact with bed below.

106 _ _ _ _ Mudstone: medium-hard, grayish-black (N 2), fissile.

105_ ___ Phosphorite: muddy, crumbly, brownish- black (5YR 2/1), thin- bedded, medium-pelletal; irregular contact with bed below.

104_ ___ Mudstone: soft, pale- brown (10 YR 5/2), thin-bedded.

103_-__ Phosphorite: muddy, soft, brownish-black (5YR 2/1), thin-bedded.

102 _ . _ _ Phosphorite: muddy, soft, dusky-yellowish-brown (10 YR 2/2), fissile, medium-pelletal.

101___- Phosphorite: soft, gray ish-brown (SYR 3/2), thin-bedded, medium- pelletal and nodular; nodules average 7 mm in diameter.

100-_-_ Mudstone: phosphatic, soft, dusVy-yellowish- brown (10 YR2/2), thin- bedded; apatite is me dium pelletal.

99-__. Phosphorite: soft, mod erate-brown (5F.R4/4), medium-pelletal.

0. 5 125. 9

1. 6 127. 5

1. 4 128. 9

129.4

129. 8

130. 1

130. 4

1. 9 132. 3

133. 4

133. 6

Uranium


Acid in- Organic soluble AhOa FezOa £07 matter


eU U

JES-6 1. 6 76. 3 8. 8 2. 0 11. 8 5.. 36 0. 002 0. 002

7 15. 6 45. 9 6. 7 2. 8 11. 1

9. 2 54. 4 9. 0 3. 3 14. 2

10 3. 8 67. 0 12. 2 3. 1 16. 8

11 18. 3 34. 4 7. 0 2. 4 14. 0

12 6. 7 60. 7 10. 3 3. 6 12. 8 4. 60

13 17. 6 36. 3 6. 5 2. 1 13. 2

132. 8 LAT-14 25. 8 28. 1 2. 9 1. 9

133. 1

. 008 . 007

. 005 . 005

OAP-9 22. 1 34. 5 4. 7 2. 3 7. 5 2. 03 . 005 . 001

0003 . 001

007 . 002

004 . 001

007 . 005

006 . 002

FSH-15 20. 2 37. 7 4. 8 1. 6 9. 0 3. 54 . 006 .002

709-931 -11

430

Bed

Rt-98

97

96_

95

94

93_

92 _

91

90_

89_

87

86-

85_



Description


Retort Phosphatic Shale Member of Phosphoria For mation Continued

Mudstone: phpsphatic, 0. 3 133.9 soft, brownish-black (5 YR 2/1), thin-bedded; apatite is medium pelletal.

Phosphorite: soft, mod- . 4 134. 3 erate-brown (5YR 3/4), thin-bedded, medium- pelletal.

Mudstone: soft, dusky- .2 134. 5 yellowish-brown (IOYR 2/2), thin-bedded.

Phosphorite: soft, dark- . 1 134. 6 gray (N 3), thin- bedded, medium pelletal; irregular contact with bed below.

Mudstone: soft, very . 8 135. 4 dusky red (IOR 2/2) to dusky-reddish-brown (IOYR 3/4), thin- bedded.

Phosphorite: muddy, . 8 136. 2 soft, moderate-yel lowish-brown (IOYR 5/4), thick-bedded, medium-pell etal.

Mudstone: soft, brownish- 2. 7 138. 9 black (5 YR 2/1), thin- bedded; contains some black (N 1) mudstone laminae. Fossil-colln. No. 10903.

Mudstone: medium-hard, . 4 139. 3 grayish-black (N 2), thin-bedded.

Mudstone: soft, brownish- . 2 139. 5 black (SYR 2/1), thin- bedded.

Mudstone: hard, grayish- . 4 139. 9 black (N 2), thick- bedded; grades from below.

Mudstone: soft, brownish- 2. 2 142. 1 black (5YR 2/1), thin- bedded; irregular con tact with bed below. Fossil-colln. No. 10902.

Mudstone: medium-hard, 1. 5 143. 6 grayish-black (AT2), fis sile. Fossil colln. Nos. 10902 and 10817.

Mudstone: medium-hard, . 9 144. 5 black (N 1), fissile; irregular contact with bed below. Fossil-colln. No. 10902.

Mudstone: medium-hard, 2. 3 147. 3 black (N 1), fissile. Fossil-colln. No. 10902.

Uranium

Sample PsOsAcid in soluble AhO 3 FeaOa LOI

Organic matter


eV U

FSH-16 20.2 35.6 5.8 2.1 10.5 _____ 0. 008 0.004

17 6. 4 60. 9 2. 5 14. 1 _______ . 005 . 003

18 26. 0 25. 5 3. 9 1. 5 3. 48 . 008 . 004

19 5.2 60.5 10.2 3.2 18. 4 _______ .005 .002

ERG-20 1.4 72.7 10.7 2.9 20. 8 ____ _ .002 .001

LAT-21 3. 5 64. 2 10. 0 3. 4 16. 4 8. 41 . 002 . 003

22 2.4 53.3 9.2 3.7 30. 1 _______ .003 .002

23 1. 6 54. 2 4. 1 30. 5 _______ . 002 . 001

24 1.4 63.2 10:9 3.7 21.1 17.45 .0005 .001



431

Uranium

Bed Description


Rt-84 _____ Mudstone: soft, brownish- black (5YR 2/1), thin- bedded.

83. _ _ _ _ Mudstone: medium-hard, dark-gray (N 3), thin- bedded.

82. _ _ _ _ Mudstone: medium-hard, laminated, dark-gray (A/"3) and brownish-black (5 YR 2/1), thin-bedded irregular contact with bed below.

81--__- Mudstone: medium-hard, dark-gray (A? 3), fissile; grades from bed below. Fossil-colln. No. 10901.

80_-___ Mudstone: medium-hard dark-gray (A7" 3), fissile; grades from bed below, Fossil-colln. No. 10900.

79_ _ _ _ _ Mudstone: medium-hard, dark-gray (A7 3), thin- bedded; grades from bed below. Fossil-colln. No. 10899.

78_ _ _ _ _ Phosphorite: muddy, me dium-hard, black (N 1) fissile; irregular con tact with bed below. Fossil-colln. Nos. 10898 and 10816.

77_____ Phosphorite: soft, grayish- brown (5 YR 3/2), fissile coarsely pelletal; irreg ular contact with bed below.

76_____ Mudstone: phosphatic, soft, pale-yellowish- brown (WYR 6/2), thick-bedded.

75_____ Phosphorite: soft, pale- brown (5YR 5/2), thick- bedded, medium pelletal; irregular contact with bed below.

74_ _ _ _ _ Mudstone: medium-hard, dark-gray (N 3), thin- bedded. Fossil-colln. No. 10897.

73_ _ _ _ _ Phosphorite: soft, brown ish-gray (10 YR 3/2), thick-bedded, medium- pelletal. Fossil colln. No. 10897.

72_ _ _ _ _ Mudstone: medium-hard, dark-gray (N 3), thin- bedded.

71_____ Phosphorite: soft, pale- olive (57 5/2), thick- bedded, medium-pelletal.

70_-___ Phosphorite and mudstone, interbedded: medium-hard medium- light-gray (N 7) thin- bedded medium-pelletal phosphorite interbedded with soft medium-gray (N 5) thick-bedded mudstone.


0.4 147.7

148.0

148. 2

1.9 150.1

8 150. 9

8 151,7

SampleAcid in-

soluble AhOs FezOs LOTOrganic

matter


eU U

ERC-25

26

4. 5 64. 3 11. 1 4. 7 20. 9

1. 6 56. 7 10. 6 4. 1 30. 6

0. 004 0. 002

. 003 . 001

27 2. 2 63. 6 9. 0 2. 8 26. 2 14. 69 . 003 . 003

28 3.8 58.0 10.0 1.9 30.0 _____ .002 .003

1. 1 152. 8 LAT-29 26. 2 24. 0 5. 6 2. 9 14. 3 . 004 . 003

153.5

153.9

1. 2 155. 1

155.2

155.4

155.6

155.9

1.3 157.2

30 31. 9 13. 8 3.9 1.9 8. 1 2. 44 . 007 . 006

31 24. 0 21. 2 5. 6 1. 5 16. 8 . 007 . 004

DAB-32 21. 3 23. 7 6. 8 1. 7 20. 0 . 006 . 004

33 16. 4 35. 0 6. 7 3. 7 19. 6 15. 10 . 004 . 004


Sheep Creek, Mont., lot 1234 Continued

Bed

Rt-69.

68.

67.

66.

65.

64.

63.

62.

Retort Phosphatic Shale Member of Phpsphoria For mation Continued

Phosphorite: muddy; up permost 0.4 ft medium- hard, medium-dark-gray (N 4), thick-bedded; middle 0.6 ft, medium- hard, brownish-black (SYR 2/1), fissile; low ermost 0.2 ft, soft, medium-gray (N 6), thin-bedded. Fossil- colln. No. 10815.

Mudstone: phosphatic, medium-hard, lami nated light-gray (N 7) and dark-gray (N 3), thick-bedded; medium- grained apatite; pellets are concentrated in light-gray laminae.

Mudstone: phosphatic, medium-hard, lami nated dark-gray (N 3) and light-gray (N 7), fissile; medium-grained apatite pellets are con centrated in light-gray (N 7) laminae.

Mudstone: medium-hard, dark-gray (AT 3), thin- bedded; contains a few laminae of medium- grained apatite pellets.

Phosphorite: medium- hard, light-brownish- gray (SYR 6/1), thin- bedded, medium-pelletal.

Mudstone: phosphatic, medium-hard, lami nated dark-gray (N 3) and light-brownish-gray (SYR 6/1), fissile; apa tite pellets are medium grained and are con centrated in the pale- brown laminae.

Mudstone: phosphatic, medium-hard, lami nated dark-gray (N 3) and light-brownish-grav (SYR 6/1), thick-bed ded; apatite pellets are medium grained and are concentrated in the pale-brown laminae.

Phosphorite: soft, light- brownish-gray (SYR 6/1), thick-bedded, finely pelletal; grades from bed below.


Uranium


Acid in soluble LOI

Organic matter


eU U

1.2 158.4 DAB-34 14.6 39.0 7.9 2.6 19.0 _____ 0.005 0.004

158. 7

159. 4

159. 7

159. S

160.4

160. 8

160. 9

ERC-35 14. 0 39. 1 8. 8 2. 5 22. 5 .005 . 004

36 14. 7 39. 8 8. 3 2. 2 19. 8 13. 72 . 005 . 005



Bed Description


Rt-61______ Mudstone: phosphatic,medium-hard, lami nated grayish-black (A 2) and medium-light- gray (N 7), thin-bed ded; apatite is finely pelletal.

60______ Mudstone: soft, brown ish-black (SYR 2/1), thin-bedded.

59______ Mudstone: phosphatic,medium-hard, lami nated grayish-black (N 2) and medium-light- gray (N 7), thin-bed ded; apatite is finely pelletal.

58-_-___ Phosphorite: soft, me dium-light-gray (A7 7), fissile, medium-pelletal.

57______ Mudstone: phosphatic,medium-hard, lami nated grayish-black (N 2) and medium-light- gray (N 7), fissile, finely pelletal; grades from bed below. Fossil-colln. No. 70814.

56______ Phosphorite: medium- hard, medium-light- gray (N 7), thick-bed ded; apatite is medium pelletal. Fossil-colln. Nos. 10895 and 10896.

55_-_.__ Phosphorite and mudstone, interlaminated: medium-hard medium- gray (N 6) phosphorite interlaminated with medium-hard dark- gray (N 3) mudstone; apatite is medium pel letal. Fossil-colln. Nos. 10813, 10894 and 18574.

54______ Mudstone: soft, grayish- brown (10 YR 4/2), thin- bedded. Fossil-colln. No. 10893.

53______ Phosphorite and mudstone, interlaminated: medium-hard light- olive-gray (57 6/1) phosphorite interlami nated with medium- hard dark-gray (A7 3) mudstone; apatite is medium pelletal; grades from unit below. Fos sil-colln. No. 10893.

52_ _____ Mudstone: medium-hard,dark-gray (N 3), thin- bedded; contains a few laminae of light-olive- gray (57 6/1) finely pelletal phosphorite. Fossil-colln. No. 10893.

Chemicas analyses (percent)

Uranium


0. 5 161. 4

SampleAcid in soluble FesOs 107

Organic matter


eU U

1 161. 5

162.0

162. 2162.6

ERC-37 18.8 23.7 6.0 2.0 25.5 ___ 0.006 0.005

5 163. 1 DAB-38 32. 3 11. 9 2. 6 1.0 7. 1

2. 2 165. 3 39 15. 5 40. 2 7. 3 2. 9 17. 0 10. 10

006

004

005

003

165.8

1. 6 167. 4

40 6. 5 72. 8 10. 2 3. 6 8. 0 003 002

8 168. 2

41 12. 3 50. 7 9. 5 2. 6 14. 2 004 004



Bed Description


Rt-51 _ _ _ _ _ Phosphorite: muddy, soft, light-brownish-grav (10- YR 6/2), thick-bedded, coarsely pelletal. Fossil- colln. No. 10893.

50_--_- Mudstone: medium-hard, grayish-black (N 2), thin-bedded. Fossil- colln. No. 10893.

49-__-_ Phosphorite: soft, pale- olive (5F 5/2), thick- bedded, medium-pelletal. Fossil-colln. No. 10893.

48 _____ Mudstone: phosphatic, soft, brownish-gray (10 YR 4/2) to brown ish-black (10 YR 2/2), fissile; apatite is medi um pelletal; grades from bed below. Fos sil-colln. No. 10893.

47_____ Mudstone: medium-hard, laminated light-brown ish-gray (10 YR 6/2), and grayish-brown (5YR 3/2), fissile; ir regular contact with unit below. Fossil- colln. No. 10892.

46_____ Mudstone: soft, brown ish-gray (10 YR 4/2), fissile; contains a few light - brownish - gray (10 YR 6/2) laminae of phosphatic mudstone; apatite in laminae is finely pelletal.

45_-___ Mudstone: medium-hard, light-brownish-gray (WYR 6/2), thick- bedded.

44_ _ _ _ _ Mudstone: medium-hard, light-brown (SYR 5/5), thick-bedded.

43_ _ _ _ _ Phosphorite: medium- hard, light-brown (5YR 5/2), thick-bedded, medium-pelletal.

42_____ Phosphorite: muddy, medium-hard, dusky- yellowish-orange (10- YR 6/6), medium pel letal; irregular contact with bed below. Fos sil-colln. No. 10812.

Franson Tongue of Park CityFormation:

F-4!__.._ Sandstone: soft, dusky- yellowish-orange (10F.R 6/6) thick-bedded; up permost 0.4 ft grayish- yellow (5F8/4).


Uranium


170. 0

1. 3 171. 3

2. 4 175. 2

6 175. 8

176.0

176.4

8 177. 2

177.7

Sample PaO8Acid \n- soluble FejOj

Organic LOI matter


«U U

1. 3 169. 5 DAB-42 15. 9 37. 4 10. 5 2. 7 17. 6 6. 39 0. 006 0. 006

43 21. 7 32. 6 6. 3 2. 5 10. 5 006 . 007

1. 5 172. 8 ERC-44 10. 4 56. 8 9. 7 3. 8 14. 5 005 006

45 6. 0 65. 7 11. 1 3. 5 16. 0 6. 50 . 005 . 004

46 6. 6 69. 5 11. 9 4. 4 10. 4 003 . 001

DAB-47 15. 0 46. 2 8. 0 7. 1 5. 6

48 27. 0 28. 7 2. 0 1. 7 2. 4 0. 10

005 . 004

012 . 010

2. 9 180. 6 49 3.4 85. 9 3. 7 2. 9 2. 5 005 . 003




435

Bed Description

Franson Tongue of Park CityFormation Continued

F-40_____ Sandstone: soft, dusky- yellowish-orange (10- YR 6/6), thin-bedded; contains irregular roughly spherical con cretions, 0.08 ft in diameter composed of black (N 2) sandstone, that comprise 15 to 20 percent of unit; irregu lar contact with bed below.

39_____- Sandstone: soft, dusky- yellowish-orange (10 YR 6/6), thin-bedded.

38_____- Sandstone: medium-hard, dusky-yellowish-orange (1QYR 6/6); contains irregular chert nodules 3 mm in diameter com prising 5 percent of rock; grades from bed below. Fossil-colln. No. 10811.

37______ Chert: medium-harddusky, yellowish-orange (10 YH 6/6) chert interbedded with medium- hard light-gray (N 8) to medium-gray (N 6) chert; bedding is ob scure and probably dis turbed by slumping; grades from bed below.

36______ Chert: hard light-olive- gray (5Y 6/1) very thick bedded chert interbedded with med ium-hard yellowish- gray (5Y 7/2) very thick bedded chert.

35--_-_- Similar to bed F-36____34-_____ Dolomite: medium-hard,

white, aphanitic; con tains a few chert nod ules in lower 1.0ft.

33______ Sandstone: dolomitic-hard, medium-gray (N 6); contains a few chert stringers.

32______ Chert: hard, brownish- gray (10Y# 4/2) and medium-gray (N 6), thick-bedded.

31______ Dolomite: medium-hard,light-gray (N 8), thin- bedded; contains nu merous chert nodules and many lenses averaging 1.5 ft in diameter.

30______ Dolomite: medium-hard,brownish-gray (10Y.R 4/2) and medium-gray (N 5); contains numer ous chert nodules, some of which are elongated perpendicular to bed ding; thickness of bed ding obscured by slump and weathering; grades from bed below.

UraniumThick ness (feet)

Cumulativethickness

(feet) SampleAcid in soluble FejOa

Organic LOI matter

2. 3 182. 9 ERC-50 3. 6 68. 6 3. 1 1. 7 9. 4

Radio-metric Chemical

e\J U

0. 001 0. 002

3. 4 186. 3

3. 8 190. 1

5. 5 195. 6

51 3.2 3. 0 2. 5 1. 6

52 2. 7 89. 2 2. 2 2. 4 1. 3

001 . 001

002 . 003

15. 0 210. 6 LAT-53 6 94. 1 2. 1 2. 4 1. 4 0005 . 001

20. 5 6. 2

231. 1237.3

54 9 91. 3 4. 1 2. 9 2. 3

2. 2 239. 5

8 240. 3

3. 8 244. 9

4. 6 248. 7

55 1. 2 32. 2 2. 0 1. 9 29. 7

0005 . 001

002 . 001

ERC-56 5 58. 8 1. 3 3. 4 16. 0 002 . 002



F-29.

28.

27.

26.

25.

24.

R-23.

22.

21.

20.

19.

Description

Franson Tongue of Park City Formation Continued

Dolomite: medium-hard, white, aphanitic.

Dolomite: medium-hard, light-gray (N 8), aph anitic ; irregular contact with bed below. Fossil- colln. No. 10891.

Dolomite: medium-hard, moderate-brown (5YR 3/4) to dark-yellowish- orange (10 YR 5/8), thin-bedded, apha nitic.

Sandstone: dolomitic, medium-hard, grayish- yellow (57 8/4), fine grained ; contains nu merous chert nodules averaging 0.2 ft in di ameter.

Dolomite: sandy, crum bly, light-gray (N 8), aphanitic, contains glauconite-; irregular contact with bed be low. Fossil-colln. No. 11715.

Sandstone: medium-hard, dusky-yellow (57 6/7), thin-bedded; contains glauconite; contains some chert lenses near top.

Rex Chert Member of Phos- phoria Formation:

Chert: sandy, soft to hard, brownish-gray (5YR 4/1), thin-bed ded; sand is very fine; contains glauconite. Fossil-colln. No. 18573.

Chert: light-yellowish- brown (10 YR 6/4) thin- bedded chert interbedded with hard medium- gray (N 5) thick- bedded chert. Fossil- colln. No. 10810.

Sandstone: hard, pale- brown (107/2 6/3), thick-bedded.

Chert: hard, strong- yellOwish-brown (107/2 5/8) to medium-gray (N 5), thick-bedded; contains some irregular beds and lenses of sand stone; grades from bed below.

Sandstone: medium-hard, light-brown (5 YR 6/4), thick-bedded. Fossil- colln. No. 11714.

Uranium


16. 5 265. 2

4. 5 269. 7

270.0

3. 3 278. 3

Sample P2O 6Acid insoluble AZ2 Os Fe2 O3 LOT

Organic matter

Radio- metric

eVChemica

U

3. 2 276. 5

1. 6 278. 9

3. 3 281. 4

290. 1

ERC-57 0. 6 23. 3 1.1 1. 1 34 3 0. 0005 0. 003

58 3. 1 35. 6 3. 0 1. 8 26. 0 .001 .001

DAB-59 5. 9 78. 3 1.1 3. 7 1. 3 002 002

60 90. 7 2. 5 4. 2 1. 3 006 001

290.5

7. 0 297. 5

2. 2 299. 7

61 2. 1 3. 9 1. 3 0005 .001

Bed

R-18.

17.

M-16.

15.

13.

12.

G-ll.

10-

Uranium

Thick ness (feet)

7.5

9.5


(feet)

307. 2 \

316. 7

.Rad/o- Aeid in- Organic metric

Sample PzOs soluble A^Os Fe2Os 107 matter eV

LAT-62 2. 2 89. 1 2. 4 2. 9 1. 6 0. 002

Chemical U

0. 001

2.0 318.7 RLP-393 2.2 85.0 9.5 3.3 4.1 ___ 0.002 0.002




Description

Rex Chert Member of Phos- phoria Formation Con.

Chert: hard, light-gray (N 8), thin-bedded.

Chert: hard, black (N 1), thick-bedded; con tains some inter beds of medium-hard medium- gray (N 6) thick-bed ded chert. Fossil- colln. No. 11713.

Meade Peak Phosphatic Shale Member of Phosphoria For mation:

Mudstone: medium-hard, dark-yellowish orange (10 Yti 6/6), thin- bedded; a lens of pelletal phosphorite 0.1- 0.2 ft thick lies 0.7 ft above base of unit.

Mudstone: phosphatic, soft, pale-yellowish- brown (10 YR 6/2), to moderate-yellowish- brown (10 YR 4/5), thin-bedded.

Phosphorite: soft, pale- brown (5FjB 4/1), thin- bedded; apatite is me dium pelletal.

Mudstone: soft, pale-yel low ish-brown (10 YR 6/2), fissile.

Phosphorite: soft, brown ish-gray (5YR 4/1), thin-bedded, medium- pelletal.

Grandeur Tongue of Park City Formation:

Mudstone: soft, pale-yel lowish-brown (10F.K 6/2), fissile.

Mudstone: medium-hard, dark - yellowish - orange (1QYR 5/8), thin- bedded.

Mudstone: dolomitic, soft, very pale orange (10 YR 8/2).

Mudstone: medium-hard, dark - yellowish - orange (IQYR 5/8), thin- bedded.

Mudstone: friable, white, thick-bedded.

Mudstone: medium-hard, dark - yellowish - orange (IQYR 6/6), thin- bedded.

Mudstone: dolomitic, soft, light-gray (N 8), thin - bedded; grades from bed below.

Dolomite: silty, medium- 10. 5 hard, grayish - orange (IQYR 7/4), dusky- yellowish-orange (10 YR 6/6) near base, thin- bedded. Fossil colln. Nos. 10807, 10808 and 10809 and 48-KPM- 29.

437

319. 3

1 319. 4

319. 6

319.8

320. 2

5. 9 326. 1

. 7 326. 8

6. 9 333. 7

63 14.5 51.2 7.2 3.2 4.3 _____ .005 .004

. 5

6. 5

334. 2

340. 7

395

394

64

LAT-65

7 90.7 8.6 2.9 3.6 _____ .001 .002

58.9 4.2 3.9 17.2 _____ .0005 .002

3 93. 0 2. 8 2. 6 1. 5

4 89. 0 2. 1 2. 5 1. 3

. 0005 . 001

. 001 . 001

6.7 347.4 DAB-66 . 3 60. 7 4.6 2.3 17.9 _-___ .0005 .001

357. 9 67 3 47.5 3.1 2.3 24.9 ----- 0.0005 0.001



Uranium

Bed


Add in soluble AZzOa LOI

Organic matter

Radio- metric Chemica

UDescription

Quadrant Formation, upper most part:

Sandstone: medium-hard, ____ ______ _________ ____ ____ ____ ____ ____ _____ ______ _____light-gray (AT 8), thick- bedded, fine-grained.

Mudstone: soft, dusky- ____ ______ _________ ____ ____ ____ ____ ____ _____ ______ _____yellowish-orange (10 YR 6/6).

Sandstone: medium-hard, ____ ______ _________ ____ ____ ____ ____ ____ _____ ______ _____light-gray (AT 8).

1 Sample LAT-78 represents the upper 10-2 ft of bed To-135.2 Sample LAT-77 represents beds To-133, Us-134, and the lower 10.2 ft of To-135.

Oil-shale analyses Sheep Creek, Mont., lot 1234

[Oil shale analyses of samples of the Eetort Phosphatic Shale Member of the Phosphoria Formation, Sheep Creek, Mont. (See immediately preceding pages for location of section, thickness and description of strata, and chemical analyses of samples.) Analyses made by U.S. Bur. of Mines Petroleum and Oil-Shale Expt. Sta., Laramie, Wyo, by the modified Fischer-Retort method. None of the samples showed a tendency to coke. LOI, loss on ignition]

Q-3.

2.

1.

Yield of products

Weight (percent)

Sample VEM-1_ _____________________

JES-5 ___ -

78

OAP-9. _____________________385_ - -10 _ 1112 13 _-__

LAT-14_-._ _________________386

FSH-15--- ___--_-161718 _ __ _ _ _ _1920

ERC-21__-____ ______________LAT-22___ -___-___ __ __

23_ _ __ _ ._ _24 . -__ _ _ _

ERC-25_387_. _2627 _ 28

LAT-29 _ _30 _ __ ___31

DAB-32 -__33__34 _ __ _____

ERC-35. _______ ___36_ _ _____ _ _ ____37___ __________________

Oil

.___-__._______ 0.

_ ____ 1

2

------________ 8.--_---________ 7.----__________ 5.--__-__.______ 1.------______._ 2.---___________ 9.-------___.___ 3.---___________ 7.

1----__________ 3.---.-__.______ 3.----_.________ 3.------._______ 4.-------__.____ 3.------._______ 5.

Water Spent Shale

3. 8 95. 1 4. 2 94. 0 4. 6 93. 2 4. 0 94. 4 6. 5 91. 34. 8 93. 3

5

07

4

9

28396728

9237375

5.45.83. 53.26.45.06. 25.23. 13.43.84. 55. 53.47.55. 67.05. 26. 04. 47.76. 54. 37. 25.67. 54. 25. 35.05.04.85. 65. 25.0

92.991. 695.795. 790. 191. 791.992. 596. 194. 894. 193.992. 195. 189. 488.989.682. 782. 987.887. 385.782. 785. 881. 391. 194. 489. 889. 088. 888.887. 087. 786. 6

Gas+loss

1. 1 1. 8 2.2 1. 6 2. 21.91.72. 1

. 81. 12. 52.61.92.3

. 81.42. 11. 62. 41. 53. 12.63. 43.93.32. 53. 15. 23. 33. 85.31. 41. 43. 02.82.92.73. 13.42.9

Gallons per ton

Oil

1 1.

'2.>1.

'0.

7

20.18.12.'4.'6.23

7.18.

i 4.7.

'8.8.

10.8.

13.

3

68

9

0

08876689

8649494

Water

9. 1 10. 1 11.0 9.6

15. 611. 512. 913. 98.47.7

15. 312. 014. 912. 57.48. 19. 1

10.813. 2

8. 118.013.416. 812. 514. 410. 518. 615.610.317. 313.418.010. 212. 712. 012.011. 513. 412. 512.0

Specific gravity of Properties of spent shale

oil at (percent of original

0. 986

. 989

.990

. 990

.989

.990

. 991

1. 002

.994

. 990

.986

.990

LOI

3.6 4.3 4.2 4. 9 5.35. 55.06.83. 53.57.36.46. 26.34. 84.74. 34. 16.44. 27.99.97.8

12. 514.810. 110.410.714. 211.913.0

6. 16. 08.07.89. 29.09.49.89.0

Ash

91. 589. 7 89. 0 89. 5 86. 087. 887.984. 892. 292. 282. 885.385. 786. 291. 390. 189.889. 885. 790. 981. 579.081.870.268. 177.776. 975. 068. 573. 968.385.088. 481.881. 279.679. 877.677.977.6

i Estimated.


Oil-shale analyses Sheep Creek, Mont., lot 1234 ContinuedYield of products

WeigH (percent)

Sample DAB-38___---___-___________.

404142

43ERC-44

4546

DAB-47____.__ _ ____________

i Estimated.

Oil Water i

______________ __ ___ 3.0______________ 2.5 5.4.__---_-_-.-__ 0.8 5.7.______.___.__ ______ 4.8.----____-___. __ _. 8.5

.-.- ____ __ ____ 5. 57 ^

______________ ______ 8.0.-.-_-_______. ______ 5.5________ _ ___ ______ 3.2. _ ____ _ -. __ 1. 5

3pent Shale (

96. 7 89.9 92. 6 94. 8 91. 1

93. 1 89. 7 88.8 94. 2 96.5 98. 5

Has+loss

.3 .2.2 0.9 .4 .4

1.4 2. 8 3.2 . .3 .

.0 .

Oallons per ton

Oil Water

7 21 6. 4 12. 9

1 1. 9 13. 7 . __ _ 11.4. ___ 20.4

..____ 13.2______ 18.0. ___ 19.2______ 13.2

7 7______ 3.6

Properties of spent shale Specific (percent of original

gravity of shale) oil at

F LOl

3.48.03.46.47.2

5. 18. 07.63.82.21.6

Ash

93.381.989. 288.483.9

88.081. 781.290.494.396.9

Spectrographic analyses Sheep Creek, Mont., lot 1284[Semiquantitative analyses of samples of the Phosphoria, Park City, and Shedhorn Formations, Sheep Creek, Mont. (See immediately preceding pages for location of

section, thickness and description of strata, and chemical analyses of samples.) Analyses made by U.S. Bur. of Mines laboratory, Albany, Oreg. In addtion to the elements listed in the table below, Sb, As, Ba, Be, Bi, Cd, Ga, Ge, Au, In, Li, Hg, Pt, Ta, Sn, and W were looked for in all samples but were not detected. Explanation of symbols: A, > 10 percent; B, 5-10 percent; C, 1-5 percent; D, 0.1-1 percent; E, 0.01 -0.1 percent; F, 0.001-0.01 percent; G, < 0.001 percent; ND, not detected]

Sample DAB-80.. .._...

79__.____.LAT-78___ _ _.

77_ __ ...76. ___.__.

ERC-75- __-._.74. _.____.73__.._._.

DAB-72_. __.__.71__.._._.70_. ......69

VEM-1.. ______2__ ______3________4________.

JES-5_-___-..6... _.___.78-____.__

OAP-9____._...385_---_-10. ______!!_______12. ______13__.____.

LAT-14.. ______386_____-

FSH-15_______.16_______.17._.-__.18__.-___.19____-__.

ERC-20__..__.LAT-21_______.

22_______.23_______.24

ERC-25____.__.387______.26_______.2728_______.

LAT-29. _______30_. ._.._.

Al._ C._ c._ c._ c._ D.. C-_ C._ C._ C._ C._ C.. C

._ c-. C__ c.- C._ c__ B._ B._ C__ c.. B__ C__ c._ c._ c.. c._ c._ c-_ C._ c._ c._ B._ C.. c.. c.. c._ c._ c._ c.. c

BFFEEEFFFFFFF

FFFFFFEFFFFFFFFFFFFEEEFFFFFFF

Ca ACCCC

CCCCCCA

DDABAACACAAAAACADDDDDEDDr>DCAA

Cr NDNDFFFEEEEEEE

DDDDEEEEEDDEDDDDDEDDDDEDEEEDE

Co NDNDNDNDNDNDNDNDNDNDNDND

NDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDND

Cb NDNDNDNDNDNDNDNDNDNDNDND

NDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDEEENDNDNDNDNDEE

Cu GGG

GGGGGGGG

GGGGGGGGGGGGGGGGCGGGGGGGGGGGG

Fe

CBBB

CCCCCC

CCf!CCCBC0CCCCCCCC0r,BBBCCccccc

Pb NDNDNDNDNDNDNDNDNDNDNDND

NDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDND

Mg

DDDDDDDDDDD

DDDDDDCDDDDDDDDDDCDDDDDCDDDDD

Mn EEEEEEEEEEEE

EEEEFFEFFFEFEEEEEFEEFEFEFFFFF

Mo FFFFFFFFFFFF

EEEEEEEEEEEFEEEEEEEEEEEEEEEEE

Ni FFFFFEEEFFFF

EEEEEEEEEEEFEEEEEEEEEEEEEEEEE

SiA

AA

A

A

A

AAAAAA

AAAAAAAAAAAAAAAAAAAAAAAAAAAAB

AgNDNDNDNDNDNDNDNDNDNDNDND

FFFFGGGGGFFFGGFFFFFFFFGGGGGFF

Na EEEEFFEFEEEE

EEEEEEEEEEEEEEEEEEEEEEEFEEEnD

Sr NDNDFFFNDNDNDNDNDNDND

NDNDNDNDEEFFFENDFNDNDNDNDNDNDNDFFFNDNDNDNDNDEE

Ti EEEEEEEEEEEE

EDEDDDDDDDEEEEDEDEDDDDEDEEEEE

VEEEEEEEEEEEE

DDDDEEEEEEDEDDDDDDDDDDDnDDDDD

Zn EENDNDNDEEEEEEE

EEEEEEEEEEEEEEEEEEEEEEEEEEEEE

ZrFEEFFFFFFFFF

EEEEEEEEEEEEEEEEEEEEEEEEEEEEE


Spectrographic analyses Sheep Creek, Mont., lot 1234 ContinuedSample

31_______.DAB-32___ _ _.

33_______.34_______.

ERC-35.______.36_______.37_______.

DAB-38_______.39_______.40_______.41_______.42_______.43_______.

ERC-44.. ______45_______.46_______.

DAB-47_._____.48-__-_-_.49____ _ .

ERC-50_______.388 _ ___.51-__ __ .52_______.

LAT-53-______.54_______.391______.390______.389______.55___ _ _.

ERC-56_______.57-.. ... ..58_______.

DAB-59 _______392______.60_______.61_______.

LAT-62_______RLP-393_ ______

63_______.395______.394______.64__..___.

LAT-65._. __ .396______.

DAB-66 _____67. _ ___.68,______.

Al._ C._ c.. c._ c._ c._ c._ c._ c._ c._ c.. c._ c._ c._ c.. c._ c._ c.- C- C.. c.. c._ c.. c. c- C._ B.. B._ B._ C.- C._ C._ c._ c._ c._ c._ c._ c._ B.. C_ C_ c_ c.. B._ B.. C._ C._ C

B FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFF

Ca AAAAA

AAAA0AAAA0CAAAB00CDD0CCA

BA

ABCC0C0AD0DD0AAC

Cr DEEEEEEEEEDDEEDDEEEEEEEFFEEEFEEEENDEEFEEFEFFFEEE

Co NDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDENDNDNDNDFFENDNDNDNDNDNDNDNDNDFNDFFNDFFNDNDND

Cb ENDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDEEENDNDNDNDNDNDNDNDNDENDNDNDNDNDENDNDND

Cu GGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

Fe

Cccc

cccccccoccccccccccBBBA

A

C0coccccBB0BBBBA0CC!

Pb NDNDNDNDNDNDNDNDNDNDEENDNDNDNDENDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDEEDNDNDNDNDNDNDNDND

MgDDDDDDDDDDDnDDDDDDDCDEEED0CC

CBBDDDDEDDDCDD0CCD

Mn FEEEFFFF,EF,EEEFFFEEEDCEEEEEDDEEEEEEEEEFEEDEEDEEE

Mo EEEEEEEFEEF,EEP,EEEFFFEFFFFFFFFFFFFFFFFFFFFFFFFFF

Ni EEEEEEEEEFEEFEEEEFFDDEEEEDnEEEEEFEFFEEEF,EEEEFFF

SiA

AAA

A

AA

AAAAAAA

AA

AA

AAAA

A

A

AA

AAAAAAA

A

A

AAAAAAA

AAAA

Ag

FGGGGGGGGGGFFGGGFGGNDGNDNDGGGGGGNDNDNDGNDGGGFFGGGGGNDNDND

Na DEEEEEEEEEEEEEFFEEEFEFFEEEEEEFFFEEEEEEnFEEEF,EEF,

Sr ENDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDFFFFFFNDNDNDNDNDNDNDFFFFFFFFNDNDND

Ti EEEF,EEEEEEEEEEDDEEEEF,EEEEDDDEEEEEEEEEDEEEEDF,F,EF,

VDnDEnnnEEEDDEDDDDEEEDEEEEEEEEEEF,EEEEEEEEF,EF,EEF,E

Zn EEEEEEENDEEEEEEEEEEEEDEEEEDDEEEEEEEEEEEEEEDEDEEE

Zr EFF,EEEF,FEEF,EFEEEFFFFEFFEEEEEEFFFFFFFEEF,EEEF,EFFF


Canyon Creek No. 1, Mont., lot 1237

[Part of Retort Phosphatic Shale Member of Phosphoria Formation measured in hand trench near Canyon Creek, SE}4 sec. 12, T. 2 S., R. 10 W., on west limb of an overturned anticline. Beds strike N. 60° W .and dip 50° SW. Measured by M. R. Klepper and sampled by E. T. Ruppel, pies analyzed for PjOs and acid insoluble by U.S. Bur. of Mines and for other constitutents by U.S. Geol. Survey. LOI, loss on ignition ]

Beaverhead County, Mont, in September 1948. Sam-

Chemical analyse* (percent)

Thick- nets (jeet)

1.0

Cumu lative

thickness (jeet)

1.0

Uranium

Sample

MRK-270

Pa0 6

7. 2

Acid insoluble Ala 1

77. 0 __

Padio- metric

08 GejOs LOI eV

__ _.__ ____ 0.002

Chemical U

0.002

Rt-5.

Bed Description

Tosi Chert Member of PhosphoriaFormation, basal bed:

To-6_ ____ Chert: hard, brownish-black(10 YR 2/1), thick-bedded.

Retort Phosphatic Shale Member ot Phosphoria Formation; base not ex posed:

Phosphorite: hard, dark-gray 1.0 2.0 (A7 3), medium-pelletal; most of rock is aphanitic and only a few pellets are apparent.

4_______ Mudstone: Phosphatic, carbon- 1. 4 3. 4atic(?), hard, brownish-black (10YR 2/1), thin-bedded; apa tite is medium pelletal.

3_--___- Phosphorite: hard, medium-dark- 1. 8 5. 2 gray (N 4), thick-bedded; coarsely pelletal.

2_______ Mudstone and phosphorite, inter- 1.0 6.2laminated: sheared fissile mudstone interlaminated with phos phorite.

!_______ Mudstone: phoshatic, soft, light- 6.0 12.2brownish-gray (WYR 5/1) to black (N 1), thin-bedded: apa tite is medium pelletal. Under lying beds not exposed.

Canyon Creek Number 2, Mont, lot 1238[Part of Retort Phosphatic Shale Member of Phosphoia Formation measured in hand trench near Canyon Creek, EJiSEJI sec. 6, T. 2 S., R. 9 W., Beaverhead County,

Mont., on overturned east limb of an anticline. Beds strike N. 5°-10° W. and dip 70° W. Measured by M. R. Klepper and sampled by E. T. Ruppel in September 1948. Samples analyzed for P 2O 5 and acid insoluble by U.S. Bur. of Mines and for other consitituents by U.S. Geol. Survey. LOI, loss on ignition]


269 34. 7 7. 2 1. 3 2. 57 1. 64 . 007 . 007

268 10. 1 47. 8 9. 7 8. 74 6. 72 . 005 . 003

267 34. 6 6. 1 2. 6 2. 40 3. 60 . 009 . 010

266 16. 3 39. 3 8. 5 5. 38 7. 74 . 006 . 006

265 19. 6 38. 7 7. 9 2. 34 7. 06 . 007 . 007

Bed

Us-5.

Rt-4_

3.

Description

Upper Tongue of Shedhorn Sandstone, basal bed:

Sandstone: cherty, fine-grained; contains chert and quartzite pebbles in basal 0.1 to 0.3 ft; irregular contact \vith bed be low.

Retort Phosphatic Shale Member of Phosphoria Formation; base not ex posed :

Clay: gougy, red; grades from bedbelow.

Mudstone and phosphorite, interlaminated: bed is crumbly and weathered; so, no detailed sub division or description is pos sible.

Mudstone and phosphorite, interlaminated: too weathered to de

scribe in detail.Phosphorite: hard, black (N 1),

thick-bedded, coarsely pelletal; underlying beds not exposed.

Thick- lativeness thickness


Uranium

RadioAcid metric Chemical

PnOi insoluble AhOs FeaOs LOI eU U

0. 2

3.0

0.2

3. 2 MRK-273 19.1 43.2 ____ ____ ____ 0.005 0.003

3. 8 7. 0

3. 0 10. 0

272 19. 1 35. 0 . 005 . 005

271 30. 8 7. 1 1. 1 0. 90 7. 08 . 007 . 007


Melrose Adit No. 2, Mont., lot 1289[Part of Retort Phosphatic Shale Member of Phosphoria Formation sampled in an adit of the Anderson Phosphate Mines, Inc., of Butte, Mont., known as Melrose Property,

in NWH sec. 5, T. 2 S., R. 9 W., Silver Bow County, Mont., in the normal limb of a northwest-trending overturned syncline. Beds Rt-7 through Rt-15 sampled at heading of a south-southeast drift, approximately 1,400 ft from portal; beds D-1 through D-5 sampled 36 ft from heading. Beds strike northwest and dip 45° SW. Meas ured by M. R. Klepper and O. A. Payne and sampled by Payne, in September 1948. Analyzed for uranium by U.S. Geol. Survey Laboratory and for other constituents by U.S. Bur. of Mines. LOI, loss on ignition]


Uranium

Bed Description

Retort Phosphatic Shale member of Phosphoria Formation; base not exposed:

Rt-15____ Mudstone: soft, light-brown ish-gray (IQYR 5/1), thin- bedded; overlain by conglom eratic-chert hanging wall that is either the basal bed of Tosi Chert Member or uppermost bed of Retort Phosphatic Shale Member.

14____ Phosphorite: muddy, hard, dark-gray (A7 3), thick-bed ded; very finely pelletal; contains thin mudstone lenses in lower 0.5 ft; grades from bed below.

13-___ Phosphorite: soft, light- brownish-gray (IQYR 6/1), thin-bedded; finely pelletal; contains a few apatite nod ules as much as 10 mm in diameter.

12_ _ _ _ Phosphorite: medium-hard, dark-gray (N 3), nodular and finely pelletal; nodules as much as 20 mm in diam eter.

11____ Mudstone: hard, dark-gray (N 3); irregular contact with bad below.

10_.__ Phosphorite: soft, very light gray (N 8), thin-bedded, med ium-pelletal.

9____ Phosphorite: medium-hard, dark-gray (N 3), thin-bed ded; medium-pelletal; irreg ular contact with bed below.

8____ Mudstone: hard, black (N 2), thin-bedded.

7____ Phosphorite: medium-hard, thick-bedded, coarsely pel letal; grades from very dark gray (A7 3) at bottom to dark-gray (A7 4) at top; ir regular contact with bed below.

6____ Mudstone: carbonatic, soft, pale-brown (IQYR 6/3), thin-bedded; irregular con tact with bed.

5____ Phosphorite: medium-hard, black (A7 2), thin-bedded, medium-pelletal; contains apatite nodules in upper most 0.1 ft; irregular con tact with bed below.

4____ Mudstone and phosphorite, interlaminated.

3____ Phosphorite: soft, dark-gray (N 3), thin-bedded, finely pelletal; may be sheared; ir regular contact with bed below.

Thick- Cumu- ness lative (feet) thickness

(feet)

0. 2 0. 2

AcidSample PzOs insolu- AhOs

bleLOI

Radio- Chemical metric U

eV

1. 3 1. 5 MRK-293 23. 9 32. 6 2. 2 2. 6 2. 14 1. 5 0. 004 0. 003

1.8

2. Q}

1 2. 1

3.0

1. 4 4. 4

1. 9 6. 3

6.7

6 7. 3

292 27. 5 16. 0 6. 3 2. 5 2. 75 006 . 003

291 33. 3 10. 1 1. 9 1. 4 3. 05 1. 8 . 007 . 006

290 3. 8 61. 7 13. 0 5. 6 .71 4. 3 . 003 . 002

289 36. 4 4. 8 1. 1 1. 1 3. 28 1. 6 . 006 . 005

228 4. 4 39. 9 10. 4 10. 0 2. 4 6. 2 . 005 . 003

287 31. 2 15. 3 3. 2 2. 0 2. 78 2. 2 . 005 . 002

8. 5286 26.2 24. 5 4. 9 2. 1 2. 3 2. 7 .007 .003


Melrose Adit No. 2, Mont., lot 1239 Continued


Cumu-Thick- lative ness thickness

(}eef) (J'eet) Sample

Uranium

Acid insolu-

PsOs ble LOI

Padio-metric Chemical

eU II

3.4 MRK-285 35. 2 .... 1.8 1. 3 3. 16 2.2 0.005 0.004

Bed Description

Retort Phosphatie Shale member of Phosphoria Formation; base not exposed Continued

Rt-2.____ Phosphorite: soft, brownish- black (10 YR 2/1), thin-bed ded; medium-pelletal; in fault contact with bed below.

!_____ Phosphorite: muddy, soft, dark-gray (N 4); finely pel letal; pellets are indistinct in hand specimen but are apparent in thin section.

Melrose Adit No. 1, Mont., lot 1240[Retort Phosphatic Shale Member of Phosphoria Formation measured in southwest crosscut 269 ft from portal of Anderson Phosphate Mines, Inc., of Butte, Mont., known

as the Melrose P_roperty, NW14 sec.Ji, T. 2 S., 9 W., Silver Bow County, Mont., on normal limb of overturned syncline. Beds strike northwest and dip 45° SW. Meas- _ . . _ . Analyzed for P2O5 and acid insoluble by U.S. Bur. of Mines, and for other con-

3. 0 12. 4 284 5. 9 2. 5 2. 1 4. 6 .005 . 004

ured by M. R. Klepper and O. A. Payne and sampled by Payne, in September 1948. stituents by U.S. Geol. Survey. LOI, loss on ignition]


Bed

To-17.

Rt-16.

15.

14.

13.

12.

11. 10.

Description

Tosi Chert Member of Phosphoria formation, basal bed:

Chert: hard, dark-gray (N 3);grades from bed below.

Retort Phosphatic Shale Member ofPhosphoria Formation:Phosphorite: cherty, brownish-

black (10YR 2/1), thin-bedded; contains pebbles of pelletal phosphorite from 15-45 mm in diameter cemented by chert; bed ranges in thickness from 0.3 ft to 0.7 ft; irregular con tact with bed below.

Mudstone: soft, moderate-yel lowish-brown (IOYR 4/4), thin- bedded; sheared.

Phosphorite: nodular and medi um-pelletal, medium-hard, dark- gray (N 3), thick-bedded; nod ules are as much as 20 mm in diameter.

Phosphorite: medium-hard, dark- gray (N 4), thin-bedded, finely pelletal.

Phosphorite: medium-hard, dark- gray (N 3), thick-bedded, finely pelletal; contains a few apatite nodules as much as 15 mm in diameter.

Clay: bluish-white-___ _________Phosphorite: muddy, medium-

hard, dark-gray (N 3), thin- bedded, finely pelletal.

Mudstone: medium-hard, dark- gray (N 3), thin-bedded.

Phosphorite: hard, dark-gray (N 3), thick-bedded, medium pel letal; irregular contact with bed below.

Thick- Cumulativeness th ickness(feet) (feet) Sample

Uranium

Acid in soluble AlsOs FesOs LOI

Radio- Chemical metric eU U

0. 5 0. 5 MRK-283 27. 4 25. 0 1. 6 2. 09 2. 04 0. 005 0. 003

282 5. 4 66. 6 9. 5 7. 05 4. 26 003 002

1.6

1.9

2.3

2.5 3.3

1. 2 4. 5

2. 1 6. 6

281 29. 1 18. 6 2. 7 2. 37 2. 16 . 006 001

280 24. 1 29. 4 5. 4 2. 96 2. 56 005 003

279 1. 1 76. 6 13. 0 6. 29 4. 68 . 002 . 001

278 28. 4 6. 4 1. 5 1. 55 1. 68 007 003


Melrose Adit No. 1, Mont., lot 1240 Continued

Bed

Thick ness (feet)

Cumu lative

thickness (feet)

Rt-7. 6.

5.4.

Pc-1.

Description

Retort Phosphatic Shale Member of Phosphoria Formation Continued Fault gouge___ .-_-_-_-_-______ 0.1 6.7Phosphorite: hard, dark-gray (N .7 7. 4

3), thin-bedded, finely pelletal. Fault gouge_________________ .2 7.6Phosphorite: soft, medium-gray 3. 9 11. 5

(N 5), thin-bedded, medium-pelletal; base of bed is gougyfault zone, several strands ofwhich cut dark mudstono andphosphorite.

Phosphorite: muddy, medium- 9. 0 20. 5hard, black (N 2), aphanitic;very few pellets are visible inhand specimen; irregular con tact with bed below.

Chert: hard, black (N 1), thin- .8 21. 3bedded.

Park City Formation; top bed:Dolomite: creamy-white.------- ____ ____


Uranium

Sample PsOsAcid in soluble AlaOs FezOs LOI

Radio- Chemkal metric ell U

MRK-277 27. 6 19. 5 4. 9 2. 51 3. 50 . 005 . 003

276 32. 0 14. 3 1. 4 1. 39 2. 70 . 006 002

275 15.8 33.7 _._. ____ ____ .005 .003

Sawtooth Mountain, Mont., lot 1241[Permian rocks measured on Sawtooth Mountain, NE >4S W}4 sec. 10, T. 12 S., R. 5 W., Beaverhead County, Mont., on overturned east limb of Snowcrest anticline. Meade Peak

and Retort Phosphatic Shale Members of Phosphoria Formation measured in hand trenches, rest of section measured from natural exposures. Beds at top of section strike N. 5° W. and dip 75° W.; beds at base of section strike N. 40° E. and dip 64° SW. Measured by F. S. Honkala, O. A. Payne and sampled by Payne, in August 1948. Analyzed for PiOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey Laboratory]


Bed Description

Tosi Chert Member of Phosphoria Forma tion: 1

To-132__ ______ Mudstone: cherty, hard, brownish- gray (IOYR 3/1), thin-bedded. Fos- sil-colln. No. 10857.

Upper tongue of Shedhorn Sandstone:Us-131________ Sandstone: cherty, hard, light-brown

ish-gray (IOYR 5/1), thin-bedded, very fine grained; contains glauco nite.

130________ Sandstone: hard, pale-brown (2.5F6/2), very thick bedded, fine-grained; contains glauconite.

129-_--____ Sandstone: hard, yellowish-gray (IOYR 7/1), very thick bedded, fine-grained; contains glauconite; grades from bed below.

128________ Sandstone: cherty, hard, light-brown ish-gray (IOYR 6/1), very thick bedded, fine-grained; grades from bed below.

127._______ Sandstone: hard, yellowish-gray (2.5F7/2), very thick bedded, fine-grained.

126________ Sandstone: hard, yellowish-gray (IOYR7/2), very thick bedded, fine-grained; grades from bed below.

125_ _______ Sandstone: hard, pale-brown (2.5F5/2), very thick bedded, fine-grained; grades from bed below.

124________ Sandstone: cherty, hard, medium-gray(N 5), thick-bedded, fine-grained.

123________ Chert: sandy, hard, medium-gray (N5), thick-bedded; grades from bed below.

122________ Chert: sandy, medium-gray (N 5),thick-bedded; sand is very fine; grades from bed below.

121________ Sandstone: hard, pale-brown (2.5F5/2), very thick bedded, fine-grained; grades from bed below.

See footnote at end of table.

Thick- ness (feet)

5.0

2. 4

4. 3

5. 0

5. 0

Cumulativethickness

(feet)

5.0

7. 4

11. 7

16. 7

21. 7

Uranium

2. 8 24. 5

5. 0

5. 0

3. 4

5. 0

5. 0

5. 0

29. 5

34. 5

37. 9

42. 9

47. 9

52. 9

Sample P.05Acid in soluble



Sawtooth Mountain, Mont., lot 1241 Continued


Bed

Us-120.

118.

116.

99.

Description

Upper tongue of Shedhorn Sandstone Continued

Sandstone: hard, light-brownish-gray (IQYR 5/1), very thick bedded, fine grained.

Sandstone: hard, pale-brown (2.5Y 5/2), very thick bedded, fine-grained; grades from bed below.

Sandstone: hard, pale-brown (2.5Y 5/2), very thick bedded, fine-grained; grades from bed below.

Sandstone: cherty, hard, medium-gray (N 6), thick-bedded, fine-grained.

Sandstone: cherty, hard, light-brown (5YR 5/6), thick-bedded; grades from bed below.

Retort Phbsphatic Shale Member of Phos- phoria Formation:

Phosphorite: sandy, hard, medium- gray (N 5), thick-bedded, very coarsely pelletal.

Phosphorite: muddy, hard, dark-gray (N 3), thick-bedded, very coarsely pelletal.

Mudstone: hard to soft, black (N 1), thin-bedded.

Similar to bed Rt-113____________Phosphorite: muddy, medium-hard,

black (N 1), thick-bedded, very coarsely pelletal.

Mudstone: soft, brownish-black (IQYR 2/1), thin-bedded.

Phosphorite: muddy, medium-hard, black (N 1), thick-bedded, very coarsely pelletal.

Mudstone: soft, brownish-black (IQYR 2/2), thin-bedded.

Mudstone: soft, black (N 1), fissile...Phosphorite: muddy, medium-hard,

dark-gray (N 3), thick-bedded, very coarsely pelletal.

Similar to bed Rt-107_____________Similar to bed Rt-106_____________Similar to bed Rt-107_____________Phosphorite: muddy, medium-hard,

dark-gray (N 3), thick-bedded, coarsely pelletal.

Mudstone: medium-hard-black (AM), thin-bedded.

Phosphorite: medium-hard, dark-gray (N 3). thick-bedded, coarsely pelletal.

Dolomite: medium-hard, light- brownish-gray (IQYR 6/2), thin- bedded, aphanitic.

Chert: muddy, phosphatic, hard, black (N 1), thin-bedded. Fossil-colln. No. 10856.

Chert: medium-hard, dusky-brown (IQYR 2/2), thin-bedded.

Mudstone: medium-hard, dusky-brown (iQYR 2/2), thin-bedded.

Similar to bed Rt-96______________Mudstone: medium-hard, dusky-brown

(IQYR 2/2), thin-bedded. Mudstone: medium-hard, dusky-brown

(IQYR 2/2), thin-bedded.Mudstone: medium-hard, brownish-

gray (5YR 4/1), thin-bedded.Chert: hard, dark-gray (N 3), thin-

bedded.

ick- '?ss set)

3. 8

5.0

5. 0

5.0

2. 5

1. 0

1. 8

1. 0

4. 6 . 5

. 5

1. 5

5.0

. 8

. 3

. 4 1. 3 2. 2

. 8

1. 2

. 3

2.0

.9

3.2

5. 0

5.0 5.0

5.0

5. 0

2. 3

-/umulQ&ivethickness

(feet)

56. 7

61. 7

66. 7

71.7

74. 2 '

75. 2

77. 0 ;

78.0

82. 6 83. 1 '

83. 6

85. 1

90. 1

90. 9 } 91. 2

91. 6 92.9 95. 1 J 95. 9 '

97. 1

97. 4

99. 4 ;

100.3

103. 5

108. 5

113. 5 118. 5

123. 5

128. 5

130. 8

Acid in- Sample PzOs soluble

FSH-438 7. 4 77. 7

437 14. 7 51. 7

436 4. 7 63. 1

435 20. 9 27. 5

434 7. 9 50. 7

433 16. 3 33. 8

432 16. 9 35. 4

431 6. 9 18. 7

430 .2 85. 7

429 .3 84. 9

428 .4 83. 7 427 .3 87. 3

426 .4 83. 3

425 .2 86. 3

Uranium

Radio- Chemical metric ell U

0. 002 0. 001

. 003 . 003

. 004 . 002

. 007 . 006

. 005 . 003

. 007 . 005

. 007 . 005

. 003 . 002

. 002 . 001

. 002 . 001

. 002 . 001

. 002 . 001

. 002 . 001

. 002 . 001

709-931 O 63- -12


Sawtooth Mountain, Mont., lot 1241 ContinuedChemical analyses (percent)

Bed Description

Lower tongue of Shedhorn Sandstone:Ls-90 _ _____ Sandstone: medium-hard, grayish-

brown (2.5YR 4/2), very thick bedded, fine-grained: contains glauconite.

89 _ _ _ Sandstone: medium-hard, pale-brown (2.5F 5/2), very thick bedded, fine grained.

88--__----- Sandstone: hard,pale-brown (2.5 Y 5/2),very thick bedded, fine-grained.

87 _____ Sandstone: medium-hard, pale-brown(2.5F 5/2), very thick bedded, fine grained.

86____---_- Sandstone: hard, dark-gray (N 3),thin-bedded, fine-grained.

85_________ Sandstone: cherty, hard, medium-gray(N 5), thin-bedded, fine-grained.

Franson Tongue of Park City Formation; contains tongue of lower member of Shedhorn Sandstone near top:

F-84__ _______ Mudstone and chert, interbedded:hard medium-gray (N 5) thin-bedded sandy chert interbedded with hard medium-gray (N 5) cherty mudstone.

83_________ Conglomerate: hard, dark gray (N 4),thick-bedded; pebbles are composed of chert and average 2 mm by 10 mm; contains phosphatic skeletal frag ments; irregular contact with bed below. Fossil colln. No. 10855.

82_______ Chert: hard, yellowish-white (10 YR9/1), thin-bedded.

81 _________ Covered-: light-gray dolomite float____80_ _ _______ Dolomite: hard, yellowish-gray (10 YR

8/1), very thick bedded, granular; grades from bed below.

79_________ Dolomite: sandy, hard, yello'nish-gray(10 YR 8/1), very thick bedded, gran ular; grades from bed below.

78_________ Dolomite: hard, yellowish-gray 1(10YR8/1), thin-bedded, granular; grades from bed below.

Ls-77_ ________ Sandstone: dolomitic, hard, weak- yellowish-orange (2.5 YR 8/4-), thick- bedded, very fine grained; grades from bed below.

76_________ Sandstone: dolomitic, hard, weak-yel low ish-orange (2.5YR 8/4), thick- bedded, very fine grained; grades from bed below.

F-75_________ Siltstone:dolomitic, hard, weak-yellowish- orange (10 YR 7/6), very thick bedded; grades from bed below.

74_________ Dolomite: bard, yellosvish-gray (2.5 Y7/2), \ ery thick bedded, aphanitic.

73_________ Dolomite: nard, yellowish-gray (2.5F7/2), very thick bedded, aphanitic; grades from bed below.

72_________ Dolomite: hard, yellowish-gray (2.5 Y7/2), thick-bedded, aphanitic; con tains phosphatic skeletal fragments; grades from bed below.

71_________ Dolomite: sandy, hard, yellowish-gray(2.5 Y 7/2), thick-bedded, granular; grades from bed below.

70_________ Dolomite: sandy, hard, yellowish- white (2.5 Y 9/2), thick-bedded, granular.

69_________ Dolomite: silty, hard, pale-brown (2.5F6/2), thick-bedded, aphanitic.

68---_--_._ Dolomite: hard, pale-brown (2.5F6/2), thick-bedded, aphanitic.


Uranium

4. 3 135. 1

5. 0 140. 1

3. 3 147. 2

3. 2 150. 4

2. 7 153. 1

. 6 153. 7

4. 0 157. 7

11.0 168.75. 0 173. 7

5. 0 178. 7

5. 0 183. 7

5. 0 188. 7

2. 5 191. 2

5. 0 196. 2

2. 6 198. 8

5. 0 203. 8

5. 0 208. 8

5. 0 213. 8

5. 0 218. 8

2. 0 220. 8

3. 0 223. 8


2.0 142.1 __________

1. 8 143. 9 FSH-424 3. 6 86. 7 0. 0005 0.001



Bed Description

Franson Tongue of Park City Formation;contains tongue of lower member ofShedhorn Sandstone near top Continued

F-67--.--.___ Chert: hard, pale-brown (2.5Y 6/2),thick-bedded.

66..__.._ Chert: hard, pale-brown (2.5F 6/2), thick-bedded; grades from bed below.

65--------- Chert: hard, pale-brown (2.5 Y 5/2),thick-bedded; grades from bed below.

64_________ Dolomite: silty, hard, pale-brown (2.5 Y5/2), thin-bedded, aphanitic.

63.---__-__ Dolomite: hard, pale-brown (2.5 Y 5/2), thick-bedded, aphanitic.

62_________ Carbonate rock: hard, yellowish-gray(5Y 7/2), thick-bedded, granular. Fossil- colln. No. 10854.

61_________ Dolomite and chert, interbedded: hardyellowish-gray (5Y 7/2) thick-bedded dolomite interbedded with hard grayish-orange (IQYR 7/4) thick- bedded chert; approximately half of unit is composed of chert.

60__-______ Similar to bed F-61, but chert com prises 75 percent of unit.

59_._______ Similar to bed F-61_______________58-________ Dolomite: hard, yellowish-gray (5Y

7/2), thick-bedded, granular; grades from bed below.

57_________ Dolomite:medium-hard, yellowish-gray(577/2), thick-bedded, granular.

56---______ Dolomite: hard, yellowish-gray (5Y7/2), thick-bedded, granular; grades from bed below.

55_________ Carbonate rock: hard, yellowish-gray(5Y 7/2), thick-bedded, granular; contains some bryozoan fragments; grades from bed below.

54-________ Dolomite: hard, yellowish-gray (5Y7/2), thick-bedded, granular; con tains a few phosphatic skeletal frag ments; grades from bed below.

53_________ Dolomite: hard, yellowish-gray (5Y7/2), thick-bedded, aphanitic; grades from bed below.

52_________ Dolomite: hard, yellowish-gray (5Y7/2), thick-bedded, aphanitic; ir regular contact with bed below.

51 _________ Dolomite: medium-hard, grayish- orange (10 YR 7/4), thin-bedded,

aphanitic.50_________ Dolomite: hard, light-gray (N 8),

thick-bedded, aphanitic. Rex Chert Member of Phosphoria Forma

tion; contains several thin tongues of lower member of Shedhorn Sandstone:

R-49-________ Chert: hard, moderate-brown (5YR4/4), thick-bedded.

Ls-48_ ________ Sandstone: soft, yellowish-gray (5Y7/2), very thick beaded, medium- grained.

R-47-._______ Chert: hard, light-gray (N 7), thick- bedded.

46_ ________ Chert: hard, very light gray (N 8),thick-bedded.

45___._____ Similar to bed R-46_ _______________44.__ _ Chert: hard, light-gray (N 8), thick-

bedded.43__ _ Similar to bed R-44_.____________42_________ Similar to bed R-44______---__-___-41_. _______ Similar to bed R-44_ _______________40_________ Similar to bed R-44____.____-_.____


Uranium

PsOsAcid in soluble


1. 1 224. 9

3. 5 228. 4

5. 0 233. 4

5. 0 238. 4

1. 6 240. 0

4. 2 244. 2

5. 0 249. 2

5. 0 254. 2

5. 0 259. 23. 0 262. 2

5. 0 267. 2

5. 0 272. 2

5. 0 277. 2

5. 0 282. 2

5. 0 287. 2

5. 0 292. 2

3. 4 295. 6

3. 7 299. 3

3. 5 302. 8

1. 4 304. 2

1. 8 306. 0

4. 4 310. 4

5. 0 315. 45. 0 320. 4

5. 0 325. 45. 0 330. 45. 0 335. 45. 0 340. 4


Sawtooth Mountain, Mont., lot 1241 Continued

Bed


Description

Thick- Cumulativeness thickness(.feet) (feet) Sample

Uranium

P208Acid in soluble

Radio- metric eV

Chemical U

Rex Chert Member of Phosphoria Forma tion; contains several thin tongues of lower member of Shedhorn Sandstone Continued

R-39__________ Chert: hard, medium-dark-gray (AT 4), 5.0 345.4thick-bedded.

38 _______ Chert: hard, medium-gray (N 5), thin- 5. 0 350. 4bedded.

37__________ Similar to bed R-38________________ 4.8 355.2Ls-36__ _______ Sandstone: hard, brownish-gray (5 YR 3.0 358.2

4/1), thin-bedded, very fine grained. R-35 _______ Chert: hard, light-olive-gray (5 Y 6/1), 1.0 359.2

thin-bedded. 34_.______ Chert: hard, light-olive-gray (5 Y 6/1), 3.8 363.0

thin-bedded. 33 _____ Similar to bed R-34________________ 5.0 368.032 _______ Chert: hard, medium-gray (N 6), thin- 5. 0 373. 0

bedded. 31 _______ Similar to bed R-32________________ 5.0 378.030 _______ Similar to bed R-32_ _____________ 5.0 383.029 .____ Chert: hard, dark-gray (N 3), thin- 5.0 388.0

bedded. Meade Peak Phosphatic Shale Member of

Phosphoria Formation: M-28_________ Phosphorite: medium-hard, dark-gray .3 388.3

(AT 3), thin-bedded, coarsely pelletal;contains phosphatic skeletal fragments. ^ FSH-423 4. 0 80. 8 0. 003 0. 002

27_________ Mudstone:soft, light-brown (5 YR 5/6), 2.8 391.1very thick bedded.

26_________ Phosphorite: soft, brownish-black .6 391.7(1QYR 2/2), thin-bedded, medium-pelletal. \ 422 5. 2 73. 6 . 004 . 002

25_ ________ Mudstone: soft, moderate-brown (5 YR 3. 0 394. 73/4), thick-bedded.

24_________ Mudstone: soft, moderate-brown (5 YR 1.5 396.23/4), thick-bedded.

23_________ Mudstone: soft, brownish-black (5YR .6 396.8 ,, 01 ~ n Rn i nn ,i2/1), fissile. 42i ' U bU' ' U

22_ ________ Mudstone: soft, moderate-brown (5 YR .7 397.53/4), thick-bedded.

21_________ Phosphorite: medium-hard, dusky- 2.7 400.2' 420 27.6 12.7 .009 .007brown (10YR 2/2), thick-bedded,very coarsely pelletal; contains phos phatic skeletal fragments.

20_________ Dolomite: phosphatic, soft, grayish- 1.2 401.4 419 10.2 24.0 .003 .001orange (IOYR 7/4), thin-bedded;apatite is very coarsely pelletal;contains phosphatic skeletal frag ments. Fossil-colln. No. 10853.

19_________ Phosphorite: medium-hard, black 2.8 404.2 418 23.5 30.3 .007 .006(N 1), thin-bedded; very coarselypelletal; contains phosphorite pebblesand phosphatic skeletal fragments.Fossil-colln. No. 10852.



Bed Description

Grandeur Tongue of Park City Formation,upper part:

G-18-________ Chert: hard, grayish-orange-pink (5 YR7/2), thin-bedded. Fossil-colln. No. 10851.

17______-___ Dolomite: medium-hard, pinkish-gray(5YR 8/1), thin-bedded, aphanitic; contains chert layer 0.2 ft thick approximately 2.0 ft above base of unit.

16_________ Dolomite: muddy, medium-hard, dark- yellowish-orange (10 YR 6/6), thin- bedded, aphanitic.

15 _________ Mudstone: soft, greenish-black (5G2/1), thin-bedded.

14_ ________ Dolomite: muddy, soft, dark-yellow ish-orange (IOYR 6/6), thick-bedded, aphanitic.

13 _________ Mudstone: dolomitic, medium-hard,light-brown (5YR 6/4), thin-bedded.

12 _________ Mudstone: dolomitic, medium-hard,light-brown (5YR 6/4), thin-bedded.

11_________ Sandstone: dolomitic, medium-hard,light-brown (5YR 6/4), thin-bedded.

10_________ Mudstone: dolomitic, medium-hard,light-brown (5YR 6/4), thin-bedded.

9_ ________ Sandstone: dolomitic, medium-hard,light-brown (5 YR 6/4), thin-bedded, very fine grained.

8_________ Sandstone: dolomitic, medium-hard,light-brown (5YR 6/4), thin-bedded, very fine grained.

?_________ Sandstone: dolomitic, medium-hard,light-brown (5YR 6/4), thick-bedded, very fine grained.

6_________ Dolomite: muddy, medium-hard, gray ish-yellow (5Y8/4), thin-bedded, aphanitic.

5_ ________ Mudstone: dolomitic, medium-hard,grayish-yellow (5 Y 8/4), thin-bedded.

4_ ________ Mudstone: dolomitic, medium-hard,grayish-yellow (5Y 8/4), thin-bedded.

3_________ Mudstone: dolomitic, medium-hard,grayish-yellow (5Y 8/4), thin-bedded.

2__ ___ Similar to bed G-3______.__________!_________ Mudstone: dolomitic, medium-hard,

grayish yellow (5T8/4), thin-bedded; underlying beds are covered.

1 Overlying beds not measured, and distance to Dinwoody contact not known.


1. 8 406. 0

4. 2 410. 2

1. 0 411. 2

. 6 411. 8

3. 0 414. 8

2. 6 417. 4

5. 0 422. 4

5. 0 427. 4

5. 0 432. 4

5. 0 437. 4

5. 0 442. 4

3. 7 446. 1

5. 0 451. 1

5.0

5.0

5.0

5. 0 5.0

456. 1

461. 1

466. 1

471. 1476. 1

Uranium

SampleAcid in


metric eTJ U


Wadhams Spring, Mont., lots 1246 and 1247[Permian rocks sampled at bulldozer trenches near Wadhams Spring, sees. 22 and 28, T. 13 S., R. 7 W., Beaverhead County, Mont., on southeast limb of anticline. Beds

R-47 to D-138 (lot No. 1246), sampled in north trench, SEHS WH sec. 22: rest of section (lot No. 1247) in south trench, SWKNEM sec. 28. Section is deeply weathered. Beds strike N. 30° E. and dip 70-80° SE. Measured by D. A. Bostwick, E. R. Cressman, and L. A. Thomas and sampled by Bostwick, Cressman, Thomas, and W. H. Wilson, in August 1948. Samples analyzed for PzOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Qeol. Survey]

Bed Description

Din woody Formation, lower part: D-138_______ Mudstone: medium-hard, dusky-yellow

(5Y 6/7), weathers pale brown (5YR 5/2), thin-bedded; breaks into platy fragments; grades from bed below.

137_______ Mudstone: medium-hard, dusky-yellow(5F 6/7), weathers dusky-yellow (5F 6/7), thin-bedded; breaks into platy fragments; grades from bed below.

136_______ Mudstone: medium-hard, dusky-yellow(5F 6/7), weathers grayish-orange (WYR 7/4), thin-bedded; breaks into

Elaty fragments, ert Member of Phosphoria Forma

tion; contains several thin tongues of Shedhorn Sandstone in upper part:

To-135_____.__ Mudstone: sandy, cherty, medium- hard, dark-yellowish-orange (10 YR 6/6); sand is fine; contains glauconite.

134________ Chert: dolomitic, medium-hard, mod erate-yellowish-brown (10F.R 5/4), thick-bedded; contains glauconite; bedding is poorly formed; grades from bed below.

133________ Dolomite: silty, cherty, medium-hard,dark-yellowish-orange (10 YR 6/6), thick-bedded, aphanitic; contains glauconite.

132________ Chert: brittle, brownish-gray (SYR4/1), thick-bedded; bedding surfaces are irregular.

131________ Mudstone: dolomitic, sandy, medium- hard, grayish-yellow (5F 8/4), thin- bedded; very fine sand concentrated in irregular laminae; contains glau conite.

Us-130-___-___ Sandstone: hard, light-gray (N 7), thick-bedded, fine-grained; contains glauconite.

To-129________ Mudstone: medium, hard, light-olive- gray (5F5/2), thin-bedded; contains numerous irregular laminae and lenses of grayish-orange (WYR 7/4) mudstone.

128_ _______ Chert: hard, moderate-yellowish-brown(WYR 5/4), thick-bedded.

127________ Mudstone: soft, grayish-orange (WYR7/4), thick-bedded.

126_ _______ Chert: medium-hard grayish-orange(WYR 7/4) thin-bedded chert interbedded with hard brittle moderate- yellowish-brown (WYR 5/4) thick- bedded chert.

125________ Chert: medium-hard, grayish-orange(WYR 7/4), thick-bedded; contains numerous lenses of hard brownish- gray (5YR 4/1) chert; grades from bed.

124__ .__ Chert: medium-hard, yellowish-gray (5F 7/2), thin-bedded; contains a few lenses of hard, light-gray (N 7) chert; grades from bed below.



UraniumThick- Cumulativeness thickness(feet) (feet) Sample Pa05

Acid in soluble


5.4

4.5

1.4

.3 0.3

1. 0 1. 3

.4 1.7

.5 2.2

2. 3 4. 5

.8 5.3

2. 9 8. 2

3. 9 12. 1

.8 12. 9

5. 2 18. 1

5. 1 23. 2 ^

4. 5 27. 7

ERG-156 1. 4 78. 5 0. 0005

155 1. 3 78. 2 .001

DAB-154 1. 4 3. 1 . 0005

153 1. 4 89. 1 0005


Wadhams Spring, Mont., lots 1246 and 1247 ContinuedChemical analyses (percent)

Bed Description

Tosi Chert Member of Phosphoria Forma tion; contains several thin tongues of Shedhorn Sandstone in upper part Con.

To-123________ Chert: medium-hard variegated white(AT 9) and grayish-orange (10 YR 7/4) thin-bedded chert interbedded with hard laminated medium-gray (N 6) and pale-brown (5YR 6/2) thin- bedded chert.

122________ Chert: medium-hard, dusky-yellow(5Y 6/7), thin-bedded; grades from bed below.

US-121________ Sandstone: hard, grayish-orange (IOYR7/4), thick-bedded, fine-grained; con tains glauconite.

120______ Covered_________--__--_---____--119__._____ Similar to bed US-121_ _____________

To-118________ Chert: medium-hard light-gray (N 8)thin-bedded chert interbedded with brittle light-brownish-gray (5 YR 6/1) thick-bedded chert.

117__-_-__- Chert: medium-hard, light-gray (N 8), thin-bedded; contains a few lenses of fine-grained sandstone.

116_ _______ Chert: brittle, light-brownish-gray(5YR 6/1), thick-bedded.

115__ ______ Chert: medium-hard pinkish-gray(5YR 8/1) to light-gray (_V 8) thick- bedded chert interbedded with brit tle light-brownish-gray (5YR 6/1) to medium-light-gray (N 7) thick- bedded chert; some beds of the brittle chert lense out within out crop.

114_____.__ Similar to bed To-115-___-________113______ Similar to bed To-115--___________112________ Similar to bed To-115. Fossil-colln.

No. 10849.Ill-------- Chert: phosphatic, hard, medium-gray

(N 6), thick-bedded; apatite is coarsely pelletal.

Retort Phosphatic Shale Member ofPhosphoria Formation:

Rt-110________ Mudstone: phosphatic, medium-hard,yellowish-gray (2.5 Y 7/2), thin- bedded; apatite is medium pelletal; beds are highly contorted and weathered; grades from bed below.

109________ Phosphorite: muddy, medium-hard,yellowish-gray (10 YR 7/1), thin- bedded, medium-pelletal; beds are contorted and deeply weathered; grades from bed below.

108_________ Phosphorite: muddy, medium-hard,dark-yellowish-orange (10F.R 6/6), thin-bedded, medium pelletal; grades from bed below; beds are contorted and deeply weathered.

107...______ Mudstone: phosphatic, soft, very palebrown (10 YR 7/2), thick-bedded, finely pelletal.

106.________ Mudstone: soft, grayish-brown (7.5 YR7/2), thin-bedded. Fossil-colln. No. 10848.


.7 35. 1

.4 35. 56. 9 42. 4

2. 2 44. 6

6. 5 51. 1

14. 1 65. 2

11. 3 76. 519. 5 96. 016. 6 112. 6

.8 113.4

1. 5 114. 9

2. 0 116. 9

Uranium

Sample

. 41 31. 8 DAB-152

2. 2 34. 0

.4 34. 4

ERG-151 1. 4

150

149

DAB-148 147 146

ERG-145

144

143


1. 3 86. 3 0. 0005

3. 7 . 0005

1. 7 90. 5 . 0005

1. 1 89. 9 . 0005

1.4 92.0 .0005 _.___--1.0 92.5 .0005 ____--.1.1 93.1 .0005 __.-.

16. 9 53. 2 . 005 0. 005

17. 0 51. 2 . 003

28. 5 20. 2 . 009 . 007

.5 117. 4 DAB-142 21. 6 31. 7 . 006 . 006

.8 118.2 141 9.9 59.6 .005 .004

3.3 121.5 140 3.9 75.9 .003 -------



Uranium

Bed

Rt-105.

104-

103-

102.

101.

100.

99..

98..

97..

96..

95_

94.

93.

92.

91.

90.

89.

88.

87.

86.

85.

84.

83.

Description

ofRetort Phosphatic Shale Member Phosphoria Formation Continued

Mudstone: soft, grayish-brown (7.5YR 3/2), fissile.

Phosphorite: medium-hard, very pale brown (IQYR 7/2), thin-bedded, finely pelletal.

Mudstone: phosphatic, soft, laminated very pale brown (10F.R 7/2) and grayish-brown (7.5 YR 3/2), fissile; apatite is finely pelletal and is con centrated in very pale brown lam inae.

Mudstone: crumbly, pale-yellowish- orange (2.5F9/4), thin-bedded.

Mudstone: soft, very pale brown (10 YR 7/2), fissile.

Phosphorite: muddy, soft, laminated very pale brown (10 YR 7/2) and pale-brown (10F.R 5/3), fissile, me dium pelletal.

Mudstone: soft, dusky-yellow (5F6/7), thin-bedded.

Mudstone: phosphatic, soft, moderate- yellowish-brown (10 FR 4/4), thin- bedded.

Phosphorite: muddy, crumbly, yellow ish-gray (2.5F8/2), thin-bedded, medium-pelletal.

Mudstone and phosphorite, interlaminated: medium-hard, brownish-gray (10 YR 3/2) fissile medium pelletal phosphorite interlaminated with medium-hard brownish-gray (10F.R 3/2) fissile mudstone.

Mudstone: phosphatic, soft, dusky- brown (10 F^ 2/2), thin-bedded.

Mudstone: soft, brownish-gray (10F.R 3/2), thin-bedded.

Phosphorite- crumbly, very pale brown (10 F^ 7/2), finely pelletal.

Mudstone: soft, brownish-gray '(IOYR 3/2).

Mudstone: medium-hard, weak-yel lowish-green (5 GY 6/2), fissile.

Mudstone: soft, pale-brown (10F.R 6/2), thin-bedded; grades from bed below.

Mudstone: soft, weak-yellowish-orange (2.5 F 7/4), very thick bedded.

Mudstone: phosphatic, soft, brownish- gray (IQYR 3/2), thin-bedded, very finely pelletal.

Mudstone: phosphatic, crumbly, lami nated very pale brown (10 YR 7/2) and grayish-brown (7.5YR 3/2), thin- bedded; apatite is finely pelletal and is concentrated in very pale brown laminae; grades from bed below.

Mudstone: soft, very pale brown (10 YR 7/2), thin-bedded.

Mudstone: phosphatic, soft, very pale brown (10YR 7/2), fissile; apatite is finely pelletal.

Phosphorite: soft, very pale brown (IQYR 7/2), thin-bedded, finely pel letal.

Mudstone: phosphatic, soft, lami nated pale-brown (IQYR 6/2) and moderate yellowish-brown (10 FR 4/4), fissile; apatite is very finely pelletal; contains hard dark-gray (N 4) chert lens 0.1 ft by 0.4 ft at base of unit.


1. 1 122. 6

. 2 122. 8

2. 2 125. 0

1. 2 126. 2

. 2 126. 4

. 5 126. 9

1. 8 128. 7

1. 5 130. 2

. 3 130. 5

. 3 130. 8

1. 0 131. 8

. 2 132. 0

. 3 132. 3

. 3 132. 6

1. 0 133. 6

. 3 133. 9

1. 6 135. 5

. 5 136. 0

. 6 136. 6

. 7 137. 3

. 5 137. 8

. 3 138. 1

3. 4 141. 5

Sample

ERC-139

138

137

DAB-136

135

134

133

132

131

ERC-130

129

128

127


14. 2 48. 0 0. 006 0. 006

3. 6 72. 9 . 002

10. 5 52. 0 . 005 . 004

4.4 71.3 .003 _______

11. 4 53. 3 . 005 . 005

17. 9 44. 3 . 006 . 006

9. 7 55. 8 . 005 . 005

14. 3 46. 1 .007 . 007

6. 2 66. 0 . 003

6. 4 65. 8 . 002

3. 5 52. 5 . 005 . 003

6. 3 63. 0 . 004

17. 1 40. 3 . 005 . 005


Wadhams Spring, Mont., lots 12^6 and 1247 Continue^

Bed

Rt-82.

81.

80.

79.

78.

77.

76.

75.

74.

73.

72.

F-71.

70.

69.

68.

67.

66.

65.

64.

Description

ofRetort Phosphatic Shale Member Phosphoria Formation Continued

Mudstone: crumbly, very pale brown (IOYR 7/2), thick-bedded; grades from bed below.

Mudstone: phosphatic, soft, lami nated pale-brown (IOYR 6/2) and light-brown (7.5YR 5/6), fissile; apatite is finely pelletal; grades from bed below.

Phosphorite: muddy, medium-hard, very pale brown (IOYR 7/2), thick- bedded.

Mudstone: soft, yellowish-gray (IOYR 8/1), fissile.

Phosphorite: soft, very pale brown (IOYR 7/2), thin-bedded, medium- pelletal.

Mudstone and phosphorite, interlaminated: soft moderate-brown (7.SYR 4/4) thin-bedded mudstone interlaminated with soft pale-brown (7.5 YR 5/2), thin-bedded finely pel letal phosphorite.

Mudstone: soft, moderate-brown (7.SYR 4/4).

Phosphorite: medium-hard, very pale brown (IOYR 7/2), thin-bedded, medium-pelletal.

Mudstone: soft, pale-brown (10 YR 5/3), fissile.

Phosphorite: medium-hard, very pale brown (IOYR 7/2), thin-bedded, finely pelletal.

Covered. Nearly entire interval is probably underlain by the lower half of the Retort Member.

Franson Tongue of Park City Forma tion:

Sandstone: dolomitic, medium-hard, yellowish-gray (10 YR 7/1), very fine grained; grades from bed below.

Dolomite: medium-hard, yellowish- gray (10 YR 7/1), aphanitic; contains a few chert nodules 0.4 ft in dia meter.

Dolomite: medium-hard, yellowish- white (10 YR 9/1), aphanitic; con tains approximately 15 percent bi valve fragments. Fossil-colln. No. 10847.

Dolomite: medium-hard, light-brown ish-gray (10Y7i! 6/1), granular, grades from bed below.

Dolomite: medium-hard, yellowish- gray (IOYR 8/1), granular; contains pelecypod fragments. Fossil-colln. No. 10846.

Dolomite: medium-hard, yellowish- gray (10 YR 8/1), thick-bedded, aph anitic; contains some sand in upper part. Fossil-colln. No. 10845.

Dolomite: medium-hard, weak-yellow ish-orange (IOYR 8/4), thick-bedded, aphanitic; contains a few pelecypod and brachiopod shell fragments. Fossil-colln. No. 10844.

Dolomite: medium-hard, yellowish- gray (25 Y 8/2), granular; grades from bed below.


Thick ness (feet)

2.3


(feet) Sample

Uranium

3.0

. 2

.7

. 2

1.2

.2

1.0

6. 5

148.4

148.6

. 4 149. 0

149. 7 ^

149. 9

151. 1

151. 3

29. 0 180. 3

181.3

187.8

13. 3 201. 1


142.3 ERG-126 5.3 75.7 0.002 _______

144. 6 125 14. 3 45. 1 . 006 0. 006

. 8 145. 4 DAB-124 16. 2 41. 3 . 003

123 ). 7 59. 0 . 005 .005

122 7.2 61. 7 . 005 005

ERG-121 0. 7 11. 3 .008 002

2. 0 203. 1

22. 5 225. 6 DAB-120 1. 2 16. 5 . 001

15. 0 240. 6

2. 8 243. 4

15. 6 259. 0

119 .8 11.3 .001

118 .6 16.0 .0005


Bed

Wadhams Spring, Mont., lots 1246 and 1247 Continued

Description


F-63.

62_

61.

60.

59_

58_

57_

56.

55.

54.

53.

52-

51.

50.

49.

48.

R-47.

46.


Mudstone : dolomitic, medium-hard,pale-yellowish-orange (25 Y 9/4),thin-bedded.

Mudstone: dolomitic, medium-hard,yellowish-gray (25 Y 7/2), thin-bedded.

Mudstone : dolomitic, medium-hard,very pale brown (10 YR 7/3), thin-bedded ; contains a few chert nodules0.4 ft in diameter.

Mudstone: dolomitic, medium-hard,pale-brown (10 YR 5/3), thick-bedded.

Mudstone: dolomitic, medium-hard,pale-brown (10YR 5/3), thin-bedded.

Mudstone: dolomitic, medium-hard,very pale brown (1QYR 7/2), thick-bedded; contains a few chert nodules0.4 ft in diameter.

Limestone : hard, pale-grayish-brown(7.5YR 6/1), thick-bedded, granular;contains a few chert nodules thathave replaced the limestone.

Dolomite: white (N 9), very thickbedded, aphanitic; approximatelyone-fourth of the uppermost 2 ft ofbed is composed of brachiopod andbryozoan skeletal fragments. Fossil-colln. No. 10843.

Dolomite: medium-hard, yellowish-gray (10 YR 8/1), granular; approximately 20 percent of bed consists ofbrachiopod and pelecypod shell fragments. Fossil-colln. No. 10842.

Dolomite: medium-hard, grayish-orange (10 YR 7/4), thin-bedded,aphanitic.

Dolomite: medium-hard, yellowish-white (10 YR 9/1), thick-bedded,aphanitic.

Dolomite: medium-hard, yellowish-white (2.5 Y 9/2), thick-bedded,aphanitic; contains several thin chertlenses 0.2 ft in diameter, 9.0 ft abovebase of bed.

Dolomite: medium-hard, yellowish-white (2.5 Y 9/2), very thick bedded,aphanitic.

Dolomite: medium-hard, yellowish-gray (2.5 Y 8/2), thick-bedded, aphanitic.

Dolomite: soft, yellowish-gray (2.5Y8/2), aphanitic.

Sandstone: dolomitic, medium-hard,light-gray (N 7), very thick bedded,fine-grained.


Chert: hard, light-gray (N 7), verythick bedded.

Chert: hard black (N 2), thick-beddedchert interbedded with medium-hardlight-gray (N 8) thin-bedded chert.

ness (feet)

4.5

3.4

9. 8

19. 4

. 9

199

6. \j

1*7. O

1Q Q

thickness (feet)

263. 5 >

266. 9

276. 7

296. 1 '

297.0

qno 9

Oil Q

1A.A- Q

Uranium

Acid in- Radio- Chemical Sample PtOs soluble metric «U U

ERG 117 .6 053.3 0.001 ___ --

116 .4 73.4 .001 _-- __

115 .7 57.0 .001 --._.__

DAB 114 .3 18.9 .0005 __..

113 .3 6. 8 . 0005 _ _____

119 .3 5.8 .0005 . -..-

12. 1 357. 0

2. 8 359. 8

9. 6 369. 4

4. 0 373. 4

7. 3 380. 7

8. 2 388. 9

1. 2 390. 1

14. 8 404. 9

17. 7 422. 6

111 .3 12. 6 . 0005

110 .2 12. 5 . 0005

109 .2 5. 9 . 0005

108 .3 21. 3 . 0005

107 1. 3 56. 5 . 001

106 .2 87. 7 . 0005

LAT-105 .7 93.9 .0005


Wadhams Spring, Mont., Lots 1246 and 1247 Continued

Bed Description

Rex Chert Member of Phosphoria Forma tion Continued

R-45 ________ Chert: hard medium-gray (N 5) thick- bedded chert interbedded with medium-hard white thick-bedded chert.

44__________ Chert: hard dark-yellowish-orange(10YR 6/6) thin-bedded chert interbedded with medium-hard dark yel lowish orange (10YR 6/6) thin-bedded chert.

43__ _ _______ Chert: medium-hard, white (Af9), thin- bedded.

42__________ Sandstone: phosphatic, hard, light- gray (N 8), thick-bedded; contains phosphatic pellets and skeletal grag- ments. Fossil-colln. No. 10841.

41 __________ Mudstone: cherty, medium-hard,white (N 9) to grayish-orange (10YR 7/4), thick-bedded. Fossil-colln. No. 10840.

40________ Chert: hard, pale-brown (5YR 5/2),thick-bedded; contains some interbedded soft grayish-yellow (57 8/4) chert.

39_.________ Chert: brittle, medium-dark-gray (N4) to light-gray (N 8), very thick- bedded.

38._________ Chert: brittle grayish-brown (5 YR 3/2)thick-bedded chert interbedded with medium-hard light-gray (N 8) thick- bedded chert.

37__________ Chert: medium-hard, pale-brown (57 R5/2), thin-bedded grades from bed below.

36__________ Chert: medium-hard, laminated gray ish-yellow (57 8/4) and medium- gray (N 5), thick-bedded.

35__________ Chert: hard medium-gray (N 5) thick- bedded chert interbedded with me dium-hard grayish-yellow (5 78/4) to white (N 9) thick-bedded chert; grades from bed below.


M-34_ ________ Phosphorite: sandy, medium-hard,pale-brown (10YR 6/2), thin-bedded, medium-pelletal; contains phosphat ic skeletal fragments; sand is very fine; grades from bed below. Fossil- colln. No. 10838.

33_ ________ Mudstone: soft, light-brown (5YR5/6), thick-bedded. Fossil-colln. No. 10839.

32_________ Phosphorite: muddy, soft, light-gray(N 7), coarsely pelletal.

31_________ Carbonate rock: medium-hard, light- gray (N 8), thick-bedded, aphanitic.

30_________ Phosphorite: soft, light-gray (N 7),thick-bedded, coarsely pelletal and oolitic; contains phosphatic skeletal fragments.

Grandeur Tongue of Park City Formation: G-29__________ Mudstone: dolomitic, soft, grayish-

orange (10 KB 7/4), thick-bedded.28__________ Mudstone: dolomitic, soft, dark-yel

lowish-orange (WYR 6/6), thin- bedded.

27__________ Carbonate rock: medium-hard, dark- yellowish-orange (10772 6/6), thin- bedded, aphanitic.




1. 4 424. 0

Uranium

Acid in- Radio- Chemical PsOs soluble metric eU U

4. 0 428. 0DAB-104

8. 2 436. 2

1. 3 437. 5 LAT-264

11. 9 449. 4 3 DAB-103

0. 7 93. 3 0. 001

10. 7 70. 0 . 002

2. 2 87. 2 . 002

1. 4 450. 8^

3. 2 454. 0

4. 6 458. 61

1. 1 459. 7

10. 6 470. 3^|

3. 7 474. 0

102

ERG-101

. 35 95. 3 . 0005

.6 93. 3 . 001

100 .3 94. 0 .0005

. 9 474. 9 99 26. 1 29. 5 . 009 . 007

3. 2 483. 1 LAT-98

. 8 483. 9 263

. 6 484. 5 (Nosample)

4. 3 488. 8 LAT-262

3. 8 492. 6'

2. 8 495. 4

4.6 74.0 .004 _--_

26.3 22.4 .011 .013

23. 2 23. 6 . 013 . 013

. 2 495. 696 .6 76. 0 .001



Bed

G-26.

25.

24_

23.

22.

21.

20.

19.

18.

17.

16.

15.

14.

13.

12.

11.

10.

Thick- Cumulativeness thickness

Description (feet) (feet)

Grandeur Tongue of Park City Formation Continued

Mudstone: dolomitic, medium-hard, 3. 5 499. 1 grayish-orange (WYR 7/4), thick- bedded.

Mudstone: dolomitic, medium-hard, . 3 499. 4 light-brown (5YR 6/4), fissile.

Dolomite: medium-hard, light-gray 2. 0 501. 4 (N 8), thin-bedded.

Mudstone: dolomitic, medium-hard, 3. 2 504. 6 grayish-orange (IQYR 7/4), thin- bedded; contains a few nodules of medium-gray (N 6) chert that are 0.15 ft in diameter.

Dolomite: hard, weak-yellow (5YR 3.3 507.9 8/4), thick-bedded, aphanitic.

Mudstone: dolomitic, medium-hard, 1. 9 509. 8 white (N 9) to grayish-yellow (5Y 8/4), thin-bedded.

Mudstone: dolomitic, hard, light-gray 4. 6 514. 4 (N 8), thick-bedded. Fossil-colln. No. 10837.

Dolomite: medium-hard, light-gray .8 515. 2 (N8), thin-bedded, aphanitic; grades from bed.

Mudstone: dolomitic, soft, dusky- 3. 4 518. 6 yellow (5Y 6/4), thin-bedded.

Mudstone: dolomitic, hard-grayish- 5. 3 523.9 orange (IQYR 7/4), thick-bedded.

Dolomite: hard, mottled medium-gray 1. 4 525. 3 (N 5) and pale-red (5R 6/2), very thick bedded, aphanitic.

Mudstone: dolomitic, soft, light-gray 2. 6 527. 9 (NS), thick-bedded.

Mudstone: dolomitic, soft, light-gray 12. 7 540. 6 (NS), thick-bedded.

Mudstone: dolomitic, soft, laminated 11. 6 552. 2 light-gray (N 8) and dark-yellowish- orange (IQYR 6/6), thick-bedded.

Mudstone: dolomitic, hard, light-gray 9. 4 561. 6 (N 8); contains lenses and nodules of dark-gray (N 4) chert 0.4 ft in diameter constituting about 20 per cent of bed.

Dolomite: medium-hard, grayish- 1.1 562.7 orange (IQYR 7/4), light-gray (N 8), very thick bedded; contains chert nodules and lenses, 0.1 ft in diameter.

Dolomite: muddy, medium-hard, mod- 2. 5 565. 2 erate-red (5R 5/4), aphanitic; con tains a few chert nodules.

Dolomite: moderate-yellowish-orange 4. 5 569. 7 (IQYR 7/4), aphanitic; contains chert lenses 0.1 ft in diameter.

Dolomite: muddy, soft, grayish-yellow 5. 7 575. 4 (57 8/4) to white (N 9), thin-bedded, aphanitic; contains medium-dark- gray chert nodules 0.15 ft in dia meter.

Dolomite and chert, interbedded: 5. 3 580. 7 crumbly grayish-yellow (5Y 8/4) thick-bedded aphanitic muddy dolo mite interbedded with brittle light- olive-gray (5 Y 5/2) to medium-dark- gray (N 4) thick-bedded chert.

Dolomite: muddy, hard, grayish-orange . 6 581. 3 (IQYR 7/4), thick-bedded, aphanitic.

Dolomite: soft, white (N 9) to grayish- 3. 2 584. 5 yellow (5Y 8/4), thin-bedded, aph anitic.

Dolomite: soft, white (N 9) to weak- 15. 0 599. 5 yellowish-orange (57 7/5), aphanitic.

Uranium

Sample

ERC-95

94

93

DAB-92

91

90

Acid in- Radio- Chemical PjOs soluble metric eU U

0. 6 51. 6 0. 002

.2 6.5 ______

.4 67. 6 . 001

.2 10. 2 . 0005

. 25 70. 1 . 002

.3 6. 7 . 0005

LAT-S

87

ERC-86

1 50. 0 . 001

1 57. 0 . 001

25 66. 6 . 002

4 72. 8 . 001

85 .4 32. 4 . 0005

ERC-84 56. 6 . 0005

DAB-83 4. 6 . 0005



Bed

G-3.

2.

Q-l-

Description


Sandstone: hard, light-gray (N 8), very thick bedded, fine-grained.

Siltstone: soft, white (N 9) to dusky- red (5R 3/4) and light-yellowish- brown (10 YR 6/4); contains small irregular chert nodules.

Quadrant Formation:Sandstone: medium-hard, light-gray

(N8) to dark-yellowish-orange (10F.fi 6/6), fine-grained.


Uranium

2. 2 601. 7

10. 2 611. 9

18. 0 629. 9

DAB-82

81

P205

0.5

Acid in soluble


85. 5 0. 001

.2 97. 6 . 000

1 Sample ERG-156 includes beds To 4132 to To 4135 and upper half of bed To-131.2 Sample ERC-155 includes beds To 4129 and To 4130 and lower half ol bed To-131.3 Sample DAB-103 represents beds R-41 and R-42.

Kelley Gulch, Mont., lot 1249

[Phosphoria and Park City Formations measured near Kelley Gulch, sec. 2, T. 6 8., R. 11W., Beaverhead County, Mont. Franson Tongue of Park City Formation measured from outcrop; rest of section measured in bulldozer trenches. A dacitic sill 2.7 ft thick occurs 2.1 ft above base of Tosi Chert Member of Phosphoria Formation; a dacitic dike 35 ft thick transects beds in upper part of Retort Phosphatic Shale Member of Phosphoria Formation. Beds strike N. 25° E. and dip 25° NW.; measured by R. L. Parker and D. A. Bostwick and sampled by R. L. Konizeski, J. E. Joyce, D. A. Bostwick, J. A. Kelleher, and E. T. Ruppel, in August 1948. Samples analyzed for PzOs and acid insoluble by U.S. Bur. of Mines, and for uranium and organic matter by the U.S. Geol. Survey]


Uranium

Bed

To-89-

88_ 87_ 86_

85_

84_

83_

82_

81_

80-

Rt-79-

78-

77.

76.

75. 74.

73.

72.

71.



Tosi Chert Member of Phosphoria Forma tion; contact with overlying Dinwoody Formation approximately located:

Chert: sandy, hard, light-brownish- 27. 0 27. 0gray (10YR 5/1) to dark-gray (N 3).

Similar to bed To-89-__-____________ 25. 0Similar to bed To-89______________ 25. 0Chert: hard, dark-gray, (N 3), thick- 25. 0

bedded. Chert: hard, dark-gray (N 3), thick- 29. 0

bedded. Mudstone: medium-hard, mottled 4. 5

gray and brown. Chert: hard, dark-gray (N 3), thick- 2. 6

bedded. Chert: hard, black (N 2), thin-bedded; 7. 4

separated from bed To-81 by daciticsill 2.7 ft thick.

Chert: hard, dark-gray (N 3), thin- 2. 1bedded.

Chert: hard, dark-gray (N 4), thin- 1. 2bedded.


Chert: phosphatic, hard, dark-gray 2. 2(N 4), thick-bedded; apatite is 10831coarsely pelletal. Fossil-colln. No.

Mudstone: plastic, grayish-brown . 2(10F/2 4/2).

Phosphorite: medium-hard, dark-gray . 5(N 3), thin-bedded, medium-pelletal.

Mudstone: plastic, grayish-brown . 2(IOYR 4/2).

Mudstone: plastic, dark-gray (N 2)__ 3. 0 Mudstone: plastic, grayish-brown . 4

(2.5 Y 3/2), thin-bedded. Mudstone: soft, brownish-black (IQYR . 4

2/1), fissile. Mudstone: soft, brownish-black (10 YR . 2

2/1), thin-bedded, grades from bedbelow.

Mudstone: plastic, grayish-brown . 3(2.5 Y 4/2).

SampleAcid Organic Radio-

insoluble matter metric e~UChemical

U

52.077. 0102.0

131.0

1 QK C

1 ^8 1

1 4.^ ^

147.6

148. 8 '

151. 0

151. 2 '

151. 7

151.9

155. 3 '

155. 7

1 KK Q

156. 2

"n A "R 99Q n ^ &^ 7 n 009

228 1. 2 91. 4 __ .0005 _._ __

227 1.4 90.7 ____ .0005 _______

99 C 1 Q QQ Q OOQ

> 224 5.6 69.3 ___ .003 _______

L T>T p 990 91 Q o« 4. n fin nod

222 2.1 74.2 __ .003 __-_---

221 4.4 76.5 ____ .003 _______


Kelley Gulch, Mont., lot 1249 ContinuedChemical analyses (percent)

Bed Description


Rt-70-________ Phosphorite: muddy, hard, dark-gray(Af 3), thin-bedded, medium-pelletal; cut by several small faults of unknown displacement; irregular contact with bed below.

69 _______ Mudstone: medium-hard, grayish- brown (10 YR 4/2), thin-bedded.

68__-----_- Phosphorite: crumbly, medium-pelletal, variegated red, brown, and yellow; bed is sheared and slickensided.

67 _________ Mudstone: soft, light-brownish-gray(IQYR 5/1).

66_________ Mudstone: medium-hard, moderate- olive-brown (5 Y 4/4).

65______-_- Mudstone: hard, laminated medium- gray (N 5) and dark-gray (N 3), thick-bedded; separated from bed Rt-64 by dacitic dike 35 ft thick.

64_________ Phosphorite: medium-hard, finely pel-letal.

63_____---_ Mudstone: light-brownish-gray (10 YR 6/1).

62 __ __ _ _ _ Mudstone: soft, brown (10 YR 3/2). _ _61_________ Dolomite: hard, dark-gray (N 4), thick-

bedded, aphanitic.60__------- Dolomite: phosphatic, hard, dark-gray

(N 4), thick-bedded, aphanitic; apa tite is medium pelletal.

59-________ Dolomite: hard, dark-gray (AT4), thick- bedded, aphanitic.

58_________ Phosphorite: hard, dark-gray (N 4),medium-pelletal.

57__---_-_- Dolomite: hard, dark-gray (AT4), thick- bedded, aphanitic.

56_________ Dolomite and phosphorite, interbedded:medium-hard dark-gray (N 3) thin- bedded aphanitic dolomite interbed ded with medium-hard light-brownish gray (10 YR 6/1) thin-bedded finely pelletal phosphorite.

55_________ Mudstone: hard, medium-gray (N 5),thick-bedded.

54_________ Mudstone: phosphatic, medium-hard,yellowish-gray (10 YR 7/1), thin- bed ded; apatite is medium pelletal; con tains a few apatite nodules as much as 26 mm in diameter.

53__________ Phosphorite: muddy, soft, medium- gray (N 6), fissile, medium-pelletal.

52__________ Phosphorite: medium-hard, medium- gray (N 6), thin-bedded, finely pelle tal; contains a few apatite nodules as much as 30 mm in diameter. Fossil- colln. No. 10830.

51__________ M udstone: phosphatic, hard, dark-gray(A7" 3), thin-bedded; contains apatite nodules as much as 20 mm in diam eter.

50__________ Mudstone: phosphatic, hard, light- brownish-gray (IQYR 5/1), thin- bedded; apatite is finely pelletal; contains a few apatite nodules as much as 30 mm in diameter.

49__________ Phosphorite: muddy, hard, black (AT 1),thin-bedded, medium pelletal; con tains apatite nodules as much as 30 mm in diameter.

48--________ Phosphorite: muddy, medium-hard,grayish-brown (2.5 Y 3/2), thin-bed ded, finely pelletal; contains apatite nodules as much as 12 mm in diam eter in lower 0.7 ft.


(jeet) (feet)

Uranium

Acid Organic Radio- Chemical insoluble matter metric e\J U

1. 1 157. 3 220 RLP-22. 9 34.6 1. 02 0. 007 0.005

1. 3

7.0

1. 3

157. 6 '

157.7

158. 1

159. 4

219

218

166. 4 DAB-217

.4

1. 8

3.6 1. 1

.9

. 8

.6

1. 1

.7

166. 8

168.6

172. 2 173. 3 '

174. 2

075.0

209

208

207

175. 6 206

176. 7 205

177. 4 204

178. 7

179. 6

180. 0

180. 5

181. 0

181. 4

203

202

6. 3 62. 5 . 006 . 003

2.3 72.7 __ .004

1. 8 82. 9 1. 04 . 002

9.8 58.0 __ .004

4. 5 65. 5 1. 63 . 004

11. 0 6. 8 .002

24.3 9.3 __ .003

6. 7 11. 6 .62 . 001

9.7 19.2 ____ .003

2. 6 6. 1 --_- . 0005

11. 9 39. 2 1. 00 . 003

201 22. 5 30. 5 __._ . 006 . 004

200 8. 9 62. 5 .003

.7 182. 1 RLP-199 19. 4 36. 5 1. 03 . 003

1. 7 183. 8 198 18. 0 38. 8 . 004






Rt-47__-_---___ Mudstone: phosphatic, medium-hard, 1. 2 185. 0 pale-brown (5YR 5/2), thin-bedded; apatite is finely pelletal and nodular; nodules have a maximum diameter of 18 mm.

46-_-_--__-_ Mudstone: phosphatic, hard, light- .6 185. 6 brownish-gray (10 YR 6/1), thin-bed ded; apatite is medium pelletal.

45__________ Mudstone: medium-hard, brownish- gray (10 YR 4/1), thin bedded.

44__________ Mudstone: phosphatic, medium-hard,brownish-gray (IQYR 4/1), fissile; apatite is finely pelletal.

43._________ Mudstone: hard, olive-gray (5F 4/1),thin-bedded.

42._________ Mudstone: phosphatic, medium-hard,olive-gray (5F3/2), fissile; apatite is finely pelletal.

41__________ Mudstone: medium-hard, dark-gray(N 3), thin-bedded.

40_________ Mudstone: phosphatic, soft, brownish- gray (10 YR 4/1), thin-bedded; apa tite is finely pelletal.

39 _________ Mudstone: phosphatic, soft, light- brown (7.5YR 5/6), fissile; apatite is finely pelletal.

38.________ Dolomite: muddy, hard, dark-gray (N 1. 7 191. 23), thick-bedded, aphanitic.

37.________ Mudstone: medium-hard, grayish- . 9 192. 1brown (2.5 Y 3/2), fissile.

36_________ Mudstone: medium-hard, light-brown- 3. 0 195. 1ish-gray (10 YR 6/1), fissile; contains a few apatite nodules as much as 30 mm in diameter.

35_________ Mudstone: phosphatic, medium-hard, . 5 195. 6yellowish-gray (10F.R 7/1), finely pelletal.

34_________ Mudstone: phosphatic, medium-hard, 1. 2 196. 8light-brownish-gray (10F.R 6/1), thin-bedded; apatite is finely pelletal.

33--_______ Mudstone: medium-hard, brownish- . 6 197. 4gray (5F.R 5/1).

32.________ Mudstone: phosphatic, medium-hard, . 8 198. 2brownish-gray (IQYR 4/1), thin- bedded; apatite is finely pelletal.

31_________ Mudstone: medium-hard, brownish- 1. 5 199. 7 ^black (IQYR 2/2), thin-bedded.

30_________ Mudstone: phosphatic, hard, brownish- .6 200.3black (5YR 2/1); apatite is finely pelletal; contains a few apatite nod ules as much as 20 mm in diameter.

29_________ Mudstone: soft grayish-brown (10 YR .6 200.94/2).

28_________ Mudstone: hard, dark-gray (N 3), 1.0 201.9thick-bedded.

27.________ Mudstone: phosphatic, medium-hard, . 4 202. 3thin-bedded; apatite is finely pel letal and nodular; nodules as much as 10 mm in diameter.

Franson Tongue of Park City Formation: F-26.________ Dolomite: cherty, hard, black (N 2), 5.0 207.3

thick-bedded, aphanitic.25-________ Sandstone: hard, light-brownish-gray 32. 2 239. 5

(10 YR 5/1), thick-bedded, fine grained; contains many irregular masses of cherty sandstone.

24.________ Dolomite: sandy, hard, light-gray (N 24. 0 263.57), thick-bedded, aphanitic; sand is fine; contains many irregular chert nodules and masses.

Uranium

Sample

RLP-197

Acid Organic Radio- Chemical PzOs insoluble matter metric eU U

16. 6 42. 9 0. 004

. 7

.2

. 6

.4

. 4

1. 1

. 5

186.3

186.5

187. 1

87. 5 >

187. 9

189. 0 ;

189. 5

196 9. 5 57. 8 1. 69 . 004 ____

195 5. 2 70. 6 __._ . 005 . 001

1 1 Q4 104 ^O 0 004

193 1. 8 20. 7 .52 . 0005

192 7.2 58.8 __ .003

191 6.4 62.9 -_.- .003

190 13. 2 49. 9 1. 73 . 003

189 9.3 59.6 ___. .003

188 7.2 61.8 __ .003

DAB-187 13. 8 52. 7 .69 . 006 . 005

(?) (?) (?)



F-23-.

R-22..

M-21.

20.

19.

18.

G-17_

13

10

Q-l.

Bed Description


________ Sandstone: hard, brownish-gray(5 YR4/1), medium-grained.

Rex Chert Member of Phosphoria Forma tion?:

________ Chert: hard dark-gray (N 4), thin- bedded.

Meade Peak Phosphatic Shale Member of Phosphoria Formation:

Phosphorite: cherty, hard, pale-brown (10YR 5/3) to dark-gray (_V 3), thick-bedded, medium-pelletal and oolitic.

________ Mudstone: phosphatic, hard, dark-gray(N 4), thin-bedded; apatite is medi um pelletal.

________ Phosphorite: cherty, hard, dark-gray(A/' 4), medium-pelletal and oolitic.

________ Phosphorite: sandy, hard, dark-gray(N 3), thin-bedded; contains a few apatite nodules.

Grandeur Tongue of Park City Formation:_________ Sandstone: cherty, hard, dark-gray

(_V 3), thick-bedded.________ Mudstone: soft, weak-yellowish-orange

(}QYR 7/6).________ Mudstone: dolomitic, hard, weak-

yellowish-orange (10 YR 8/4), thick- bedded; irregular contact with beti below.

________ Mudstone: dolomitic, hard, medium- gray (N 5), thick-bedded.

________ Sandstone: dolomitic, hard, medium- gray (N 5), thick-bedded.

________ Mudstone: dolomitic, hard, very palebrown (10 YR 7/3), thin-bedded.

________ Sandstone: dolomitic, hard, reddish- purple, thin-bedded, very fine grained.

________ Mudstone: dolomitic, hard, weak- yellowish-orange (2.5 Y 7/4), thick- bedded.

________ Mudstone: dolomitic, medium-hard,very pale brown (10 YR 7/3) to moderate-brownish-orange (10 YR 6/6), thin-bedded.

--_-____ Mudstone: dolomitic, medium-hard, very pale brown (10 YR 7/3) to moderate-brownish-orange (10 YR 6/6), thin-bedded.

.--_-____ Mudstone: dolomitic, hard, weak- orange (7.5 YR 7/4), thick-bedded.

________ Mudstone: dolomitic, hard, pale-brown(10 YR 7/4), thick-bedded.

_________ Sandstone: hard, moderate-brownish- orange (10 YR 6/6), thick-bedded.

.-_______ Sandstone: medium-hard, weak-yel lowish-orange (10 YR 7/6), thick- bedded; contains lenses 'of cherty sandstone.

_________ Sandstone: medium-hard, light-yel lowish-brown (10 YR 6/5) to moder ate-yellowish-brown (10 YR 5/6), thick-bedded.

_________ Sandstone: hard, grayish-orange (10 YR7/4).

Quadrant Formation:._-_-____ Sandstone: hard grayish-orange (10 YR

7/4), thick-bedded.

Thickness (feet)

.3

.7

1.0

. 2

.4

. 2

Q 7

4.2

1 /~k c

Q 1

Q Q

2.8

1. 5

2.8

10. 4

17. 7

13. 9

9.8

2. 6

3. 7

17. 3

1.8

K. n

thickness (feet)

263.8 '

264. 5

265. 5

265. 7 '

266. 1

266. 3

07/1 n

974. 9

9SA S

OQ7 Q

9Q1 9

294.0

295. 5

298.3

308.7

326.4

340. 3

350. 1

352.7 ^

356. 4

373. 7

375. 5

Q«n K

^4dd Sample PjOs insoluble

DAB-186 2. 9 82. 3

RLP-185 27. 9 21. 9

184 22. 4 31. 9

1 QQ 9 A ftf» 7

T» A T> 1 OO 1 fl Q7 ^

181 .6 73. 4

1 Qfl Q 7Q f»

1 TO 1 T£l 1

"RT P 1 7S 1 7*^ fi

m i 79 «

1 1 7R ^l 7^ R

|> DAB-175 .3 94. 9

174 .2 85.6

175 2 Q7 2

frawmro

Organic Radio- Chemical matter metric eV U

___. 0.002 _______

____ .010 0.008

____ .007 .006

____ .0005 __--__.

____ .002 ._._.__

____ .002 ___-...

____ .001 -------

____ .002 .-_-_-.

.002 ----- _

____ .002 _____..

.002 __ _

____ .0005 ----- .

.0005 .

.000 ___ .-


Spring Creek, Mont., lot 1251[Part of the Meade Peak Phosphatie Shale Member of the Phosphoria Formation sampled by F. S. Honkalaand O. A. Payne, in August 1948, and measured by Honkalaand

R. W. Swanson, in September 1953, from the south bank of the east fork of Odell Creek, NWJiSEli sec. 5, T. 15 S., R. 1 W., Beaverhead County, Mont. Beds strike about N. 85 W. and dip 12° S. Analyzed for PzOs and acid insoluble by U.S. Bur. of Mines and for other constituents by U.S. Qeol. Survey. LOI, loss on ignition]

Bed

M-12.

11.

10.

G-3.

2.

1.

Description

Meade Peak Phosphatie Shale Member of Phosphoria Formation; top not exposed:

Limestone: medium-hard, thick- bedded, finely crystalline, yellow ish-gray (2.5F 8/2); contains quartz sand; weathers soft and spongy.

Phosphorite: medium-hard, thin- bedded, coarsely oolitic to nodu lar, pale-brown (2.5 Y 5/2); con tains Lingula.

Mudstone: soft, fssile, weak-yel lowish-orange (2.5F 8/4); con tains grit-sized quartz; in mid dle is thin bed of hard medium- pelletal pale-brown (2.5F 6/2) phosphorite.

Limestone: medium-hard, thin- bedded, medium coarsely crys talline, pale-brown (2.5 F 6/2); contains quartz sand.

Mudstone: soft, fssile, light-yel lowish-brown (WYR 6/4).

Phosphorite: medium-hard, thin- bedded, coarsely oolitic and pelletal to nodular, pale-brown (2.5F 6/2) to light-brownish- gray (WYR 6/1); thin muddy zone near middle.

Phosphorite: medium-hard, thick- bedded, coarsely oolitic, light- brownish-gray (10 YR 6/1); soft friable zone at base.

Mudstone and phosphortie: upper half sandy hard fine to medium coarsely pelletal phosphorite overlying hard mudstone, both pale-brown (2.5 F 6/2); lower half soft thin-bedded pale-brown (2.5 F 5/2) mudstone, containing small phosphate nodules; clayey at base.

Phosphorite: hard, thick-bedded, coarsely oolitic, pale-brown (2.5F 6/2) to yellowish-gray (2.5F 7/2); contains abundant shell fragments (fish scales?); chert pebbles common in lower 0.3 ft; basal contact irregular.

Grandeur Tongue of Park City Forma tion, upper part:

Limestone: hard, dense, yellowish- gray (WYR 8/1), locally silty.

Limestone: hard, massive, dense, light-gray (N7).

Sandstone: calcareous, medium- hard, very fine grained, very pale orange (WYR 9/2).


Cumu-Thick- lative ness thickness (feet) (feet) Sample

Uranium

Acid insoluble AhOa LOI


eU U

0. 9 0. 9

1. 2

1.6

2.0

.2 2. 2

1. 6 3. 8

1. 8 5. 6

60.

1.0 7. 0

FSH-261 31.3 10.9 0.97 0. 81 3.90 0. 012 0. 010

.4 7.4

1. 6 9. 0

.5 9.5

709-931 O 63- -13


Odell Creek, Mont., lot[Uppermost part of Phosphoria Formation sampled and lower part of Dinwoody Formation measured in hand trench on west side of Odell Creek, SEJ4 sec. 1, T. 15 S., R.

2 W. Beaverhead County, Mont., on southward tilted Centennial Mountains fault block. Beds strike N. 82° E. and dip 30° S. Measured by F. S. Honkala and O. A. Payne and sampled by Payne and J. A. Kelleher in July 1948. Descriptions based entirely on field notes and analytical data. Analyzed for PjOs and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Qeol. Survey]


Bed

D-51_

50.

49.

48.

47.

46.

45.

44.

43.

42.

41.

40.

39.

38.

37.

36.

35.

34.

33.

32.

31.

30.

29.


(feet) (feet)

2.1

4.9

7.5

10.4

13.0

Description

Dinwoody Formation, lower part:Limestone: medium-hard, thin- to thick-bedded, 2. 1

dusky-yellow (5F6/4). Limestone: medium-hard, thick-bedded, dusky- 2. 8

yellow (5F6/4). Mudstone: plastic to crumbly, thin-bedded, 2. 6

light-olive-gray (5F5/2). Limestone: medium-hard, thick-bedded, dusky- 2. 9

yellow (5 Y 6/4); contains shel fragments. Limestone: medium-hard, thin- to thick-bedded, 2. 6

finely crystalline, light-olive-gray (5F 6/1);contains shell fragments.

Dolomite: hard, thick-bedded, finely crystalline, 1. 0 14. 0medium-gray (N 6).

Limestone: hard (some soft layers at middle), 5. 0 19. 0thin- to thick-bedded, yellowish-gray (5 Y 7/2);contains Lingula sp.

Mudstone: calcareous, plastic to medium-hard, 4. 9 23. 9thin-bedded, moderate-yellowish-brown (WYR5/4) to grayish-brown (10 YR 4/2).

Limestone: sandy, medium-hard, thick-bedded, 2. 2 26. 1medium coarsely crystalline, yellowish-gray(5F 7/2); sand, medium to coarse; containsLingula.

Mudstone: calcareous, somewhat sandy, soft, .5 26. 6fissile to thin-bedded, light-olive-gray (5YR5/2).

Dolomite: silty, hard, thin- to thick-bedded, 4. 5 31. 1dense to finely crystalline, grayish-orange(10 YR 7/4) to light-brownish-gray (10 YR6/1); contains pelecypod casts.

Dolomite: hard, thin- to thick-bedded, aphani- 5. 0 36. 1tic, very light gray (N S) to medium-light- gray (N 6); weathers dark reddish brown (IOR3/4); contains 0.3 ft calcareous medium-hardfissile to thin-bedded mudstone, 2.8 ft abovebase; contains shell fragments.

Dolomite: hard, thin- to thick-bedded, aphani- 3. 3 39. 4tic, yellowish-gray (5 F 7/2); weathers moder ate brown; middle 0.7 ft, medium-light-gray(N 6), weathers light brown (5YR 6/4); con tains Lingula.

Dolomite: hard, thin to thick-bedded, aphanitic, 5. 0 44. 4light-gray (N 8); weathers pale reddish brown(10R 5/4); contains shell fragments.

Dolomite: hard, thin-to thick-bedded, aphanitic, 2. 2 46. 6medium-light-gray (N 7); weathers palereddish brown (IOR 5/4); contains Lingula.

Mudstone: calcareous, soft, fissile to thin- .5 47. 1bedded, grayish-brown (10 YR 4/2).

Dolomite: hard, thin-bedded, finely crystalline, 1. 8 48. 9light-olive-gray (5 F 6/1); contains Lingula.

Dolomite: hard, thin- to thick bedded, finely 3. 3 52. 2crystalline, light-brownish-gray (SYR 6/1);contains abundant Lingula.

Limestone: medium-hard, thin-bedded and 1.8 54.0flaggy, light-brownish-gray (IOYR 6/1); con tains shell fragments.

Dolomite: hard, finely crystalline, light-olive- 1. 0 55. 0gray (5F6/1).

Limestone: silty, medium-hard, thin-bedded and 1. 0 56. 0flaggy, light-olive-gray (5F 5/2).

Dolomite: hard, thick-bedded, finely crystalline, 1. 4 57. 4light-olive-gray (5F5/2).

Mudstone: upper 1.3 ft hard, fissile to thin- 3. 2 60. 6bedded, medium-gray (N 5); lower 1.9 ftdolomitic, soft, fissile to thin-bedded,brownish-gray (SYR 4/1); contains shellfragments.

SampleAcid

insoluble

UraniumRadio-

metric eU


Odell Creek, Mont., lot 1252 Continued

Bed Description

Dinwoody Formation, lower part ContinuedD-28________ Dolomite and mudstone: upper 0.4 ft thin-

bedded hard finely crystalline medium-dark- gray (AT 4) dolomite, underlain by 0.1 ft plastic to fissile medium-gray (N 5) mudstone; con tains shell fragments.

27________ Dolomite: hard, thick-bedded, finely crystalline,medium-dark-gray (N 4), weathers to dark- reddish-brown (10.R 3/4); soft mudstone parting below middle; contains shell frag ments.

26 _______ Dolomite: hard, thick-bedded, finely crystalline,medium-gray (N 5); contains shell fragments and calcite veinlets.

25 _______ Dolomite: hard, thick-bedded, finely crystalline,medium-gray (N 5); contains Lingula in upper part and calcite veinlets.

24__________ Dolomite and mudstone, interbedded; hardthin- to thick-bedded medium-gray (N 5) dolomite (60 percent) and soft fissile to thin- bedded brownish-black (SYR 2/1) mudstone.

23__________ Dolomite: hard, thick-bedded, finely crystalline,dark-gray (N 3).

22. ______ Dolomite: hard, dense, fine-grained, thick-bed ded, medium-dark-gray (N 4); contains 1 mm to 1 cm fractures filled with calcite.

21 _______ Dolomite and mudstone: 0.2 ft of medium-hardfine-grained medium-dark-gray (N 4) mudstone overlying 1.4 ft of hard aphanitic thin- to thick-bedded dark-gray (N 3) dolomite.

20__________ Mudstone: carbonatic, thick-bedded, hard,medium-gray (N 5).

19 ______ Mudstone: medium-hard, thin- to thick-bedded,grayish-brown (10 YR 4/2).

18 ______ Mudstone: upper 0.9 ft, medium-hard, thin-bedded, dark-gray (N 3); lower 1.3 ft, soft, thin-bedded, moderate-yellowish-brown (10 FB 5/4).

17 ______ Carbonate rock and mudstone: 0.7 ft of hardthin-bedded moderate-yellowish-brown (10 YR 5/4) carbonatic mudstone underlain by 1.7 ft of medium-hard dense thin-bedded grayish-red (5R 4/2) carbonate rock. Contains Lingula, Monotis, and Aviculopectin.

16 ______ Mudstone: carbonatic, plastic, thin- to thick- bedded, grayish-brown (10 YR 4/2); top 0.5 ft brecciated(?) and may be fault zone. Basal contact may be fault zone.

15__________ Mudstone and limestone: 1.6 ft of plastic poorlybedded moderate-brown (SYR 4/4) finely oolitic calcareous mudstone underlain by 0.2 ft of hard pale-brown (5 YR 5/2) aphanitic muddy limestone.

14 ______ Carbonate rock: muddy, plastic, thin-bedded,grayish-brown (10 YR 4/2) to grayish,red (10R 4/2), finely oolitic.

13__________ Limestone: medium-hard, thin-bedded, lami nated, grayish-red (10.R 4/2), coarsely oolitic.

12 ______ Mudstone: calcareous, plastic, light-olive-gray(5F 5/2).

11 ______ Limestone: medium-hard, thick-bedded, locallylaminated, moderate-brown (5YR 3/4), oolitic; contains unidentified shell fragments; emits strong petroliferous odor on striking with hammer.

10 _ _ _____ Limestone: muddy, soft, fissile, moderate-yellow ish-brown (10 YR 5/4); contains unidentified shell fragments.


(feet)

0.5

2. 0

1.7

1. 4

3. 1

1. 6

2. 1

2. 2

2.4

2. 6

1.5

.2

1. 0

61. 1

1. 3 62. 4

64.4

66. 1

3. 0 69. 1

85.3

1. 8 87. 1

3. 6

89.4

89.6

90.6

90.9


Uranium

Sample PsOsAcid

insolubleRadio-

metric e~U

70.5

73.6

75.2

77.3

78. 1

80. 3

82. 7 FSH-417 0. 6 17. 6 0. 0005

416

415

414

413

412

411

410

.4 57. 1

.3 49. 2

.4 45. 0

.7 15. 6

.5 50. 6

.7 11.6

. 75 29. 6

002

002

002

0005

002

005

001


Odell Creek, Mont., lot 1252 Continued

Bed Description


(feet) (feet)


Uranium

D 9__

To-6.

5.

Dinwoody Formation, lower part ContinuedLimestone: medium-hard, muddy, laminated to 1. 3 92. 2

thick-bedded, moderate-brown (5YR 3/4)very coarsely oolitic; contains shell fragments;lower 0.3 ft, soft, pale-yellowish-green (IOGY7/2) to moderate-yellowish-brown (10 FK5/4).

Mudstone: calcareous, soft, fissile to thin-bedded, . 6+ 92. 8 +dusky-yellow (5F 6/4). Small diagonal faultat base; so, true thickness is unknown.

Mudstone: calcareous, soft, moderate-yellowish- 1. 6+ 94. 4 +brown (10FR 5/4); irregular basal contact.contact. Total thickness unknown due tofault contact with overlying bed.

Tosi Chert Member of Phosphoria Formation, top part:

Chert: hard, brittle, fissile to thin-bedded, 1.4 1.4moderate-brown (5FK 4/4).

Mudstone: medium-hard, fissile to thin-bedded, 4. 5 5. 9cherty, light-olive-gray (5F 5/2); basal 0.5 ft,soft to hard, medium-dark-gray (N 4) tomoderate-brown (5YR 3/4); basal contactgradational.

Chert: hard, dark-gray (N 3), thin-bedded___ 1. 5 7. 4 Sandstone and mudstone: .25 ft soft light-olive- .7 8. 1

gray (5F 6/1) mudstone underlain by 0.25 ftmedium-hard fine-grained light-brownish-graysandstone.

Sandstone?: soft, crumbly, not bedded, grayish- .7 8. 8black (N2) to strong-brown (5F4/8); containsshell fragments.

Chert: hard, thick-bedded, medium-dark-gray 2. 6 11.4(AT 4).

Acid Radio- Sample PiOs insoluble metric e\5

FSH-409 0.4 38. 5 0. 0005

408 .2 70. 0 . C02

407 .9 78. 9 .001

406 1. 8 86. 7 . 0005

OAP-405 1. 5 84. 0 . 001

404 1. 05 90. 6 . 0005403 1. 3 89. 3 . 0005

402 4. 6 82. 9 . 0005

401 .4 94. 8 . 0005

Centennial No. 1, Mont., lot 1253[Phosphoria, Shedhorn, and part of Park City Formation measured and sampled in hand trench near crest of Centennial Mountains, NW cor. sec. 33, T. 14 S., R. 1 W.,

Beaverhead County, Mont. Beds strike east and dip 20° S. on Centennial Mountains fault block. Measured by P. S. Honkala and O. A. Payne and sampled by J. A. Kelleher, in July 1948. Descriptions based entirely on field notes and analytical data. Analyzed for PzOs and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Geol. Survey]


Uranium

Bed

D-59.

58.

57.

56.

55.

To-54.

53-

52,

51.

Description

Dinwoody Formation, lower part:Limestone: hard, thick-bedded, me

dium-gray (N 5); weathers dark- yellowish orange (IOYR 6/6).

Mudstone: calcareous, medium-hard, fissile to thin-bedded, medium-gray (N 5); contains laminae of strong- yellowish-brown (WYR 5/8) siltstone.

Mudstone: medium-hard, thin-bedded, silty, medium-light-gray (N 6).

Mudstone: calcareous, medium-hard, fissile to thin-bedded, silty, medium- gray (N 5).

Mudstone: calcareous, medium-hard, fissile to thin-bedded, medium-gray (N 5) to medium-light-gray (N 6). Sharp plane contact at base.


Chert: hard, thick-bedded, medium- gray (N 5); arbitrary basal contact.

Chert: hard, thick-bedded, dark-gray (N 3); gradational basal contact.

Chert: hard, thin-bedded, olive-gray (5F 4/1); arbitrary basal contact.

Chert: hard, thin- to thick-bedded, olive-gray (5F 4/1); arbitrary basal contact.

Thick ness (feet)

0.7

2. 8

2. 5

3. 4

2.0

Cumulativethickness

(feet) SampleAcid in

solubleRadio-

metric eUChemical

U

0. 7 OAP-496

3. 5

6.0

9.4

11. 4

495

494

493

492

0.8

1.3

1. 4

1. 3

1.3

79. 7 0. 0005 0. 0005

75. 7

74.6

75.0

001

001

001

001

0005

0005

0005

0005

1. 5

3. 5

4. 1

3. 2

1.5

5.0

9. 1

12.4

491

490

489

488

1.0

. 3

. 5

.7

77. 7

95. 3

83. 3

90. 2

.0005

.0005

.0005

.0005

.0005

.0005

.0005

.0005


Centennial No. 1, Mont., lot 1253 Continued

465


Bed Description

Tosi Chert Member of Phosphoria Forma tion Continued

To-50_________ Chert: hard, massive, olive-gray (5F4/1); arbitrary basal contact.

49_________ Chert: hard, massive, brownish-gray(5YR 4/1); contains chalcedonic veinlets; arbitrary basal contact.

48_________ Chert: hard, thin- to thick-bedded, me dium-dark-gray (N 4); locally lami nated; arbitrary basal contact.

47.________ Chert: like bed To-48; contains lami nated mudstone parting above middle.

46_________ Chert: like bed To-48; contains lami nated mudstone partings.

45______ Chert: like bed To-48_______---___-44_________ Mudstone: calcareous, hard, fissile to

thin-bedded, silty, medium-light- 'gray (N 6).

43_________ Dolomite: silty, hard, thick-bedded,aphanitic, medium-gray (N 5).

42_________ Chert: hard, thin- to thick-bedded,medium-dark-gray (N 4); arbitrary basal contact.

41_________ Chert: hard, thin-bedded, medium- dark-gray (N 4).

40_________ Carbonate rock: hard, thin-bedded,coarsely crystalline, medium-light- gray (N 6).

39-____.___. Chert: like bed To-41-_._____________38_________ Carbonate rock: like bed To-40___37_________ Chert: like bed To-41; arbitrary basal

contact.36_________ Chert: hard, thin- to thick-bedded,

medium-dark-gray (N 4); contains calcareous mudstone partings; arbi trary basal contact.


Rt-35_________ Mudstone: cherty, hard, thin- to thick- bedded, dark-gray (N 3).

34.________ Limestone: muddy, hard, thick-bedded,coarsely crystalline, dark-gray (N 3).

33_________ Chert: hard, thin-bedded, medium- dark-gray (N 4).

32_________ Limestone: muddy, hard, thin-to thick- bedded, coarsely crystalline, grayish- black (N 2).

31_________ Mudstone: hard, fissile to thin-bedded,grayish-black (N 2); arbitrary basal contact.

30_________ Mudstone: cherty, hard, fissile to thin- bedded, dark-gray (N 3); arbitrary basal contact.

29_________ Mudstone: medium-hard, thin-bedded,dark-gray (N 3); arbitrary basal contact.

28 _________ Mudstone: medium-hard, fissile tothin-bedded, silty, grayish-black (N 2); gradational basal contact.

27_________ Mudstone: medium-hard, fissile tothin-bedded, dark-gray (N 3); contains thin grayish-black (N 2) bands; arbitrary basal contact.

Mudstone lens: hard, massive, medium- gray (N 5); about 3 ft long.

26_________ Mudstone: hard, fissile to thin-bedded,medium-dark-gray (N 4); arbitrary basal contact.

25_ ________ Mudstone: hard, thin-bedded, medium- dark-gray (N 4); gradational basal contact.

24__.______ Mudstone: medium-hard, fissile, gray ish-black (N 2).

Thick ness (feet)

2.9

5.0

Cumulativethickness

(feet)

15.3

20.3

Uranium

5. 0 25. 3

5.0

5. 0

5.0 1.0

2. 2

4. 2

.7

.3

2. 51. 0

. 5

5.0

30.3

35.3

40. 341.3

43. 5

47.7

48.4

48. 7

51. 252. 252. 7

57. 7

SampZe

GAP-487

FSH-486

485

484

483

482

481

480

P.Os

0.5

.6

.6

.5

.5

. 5

Acid insoluble

Radio- metric eU

093. 5 0. 0005

93. 3 . 0005

88.0

86. 7

86.7

85.2

50. 7

84.3

0005

0005

0005

0005

0005

0005

Chemical U

0. 0005

.0005

.0005

.0005

.0005

.0005

.0005

.0005

479

478

82. 3

77.0

0005 .0005

0005 .0005

2. 1

1. 4

1.0

1. 5

2. 5

5.0

3.3

2. 2

1. 2

(0-1. 0)

4.6

2.0

1.7

59. 8 '

61. 2

62. 2 <

63.7

66.2

71.2

74.5

76.7

77.9

82. 5

84. 5

86.2

477

476

475

OAP-474

473

472

471

470

469

. 5

. 6

. 8

1.0

.9

1. 5

. 6

2.2

3.3

76.2

81.7

77.3

76.0

77. 5

74.7

69.0

71.7

67.9

.0005

.0005

.001

.001

.002

.003

.002

.003

.003

.0005

.0005

.0005

.001

.001

.001

.001

. 201

.002



Bed Description


Rt-23-_------- Mudstone: medium-hard to crumbly,fissile, dark-gray (N 3).

22 _________ Phosphorite: soft, thin- to thick- bedded, medium coarsely pelletal, medium-gray (N 5).

21_-__-____ Mudstone: carbonatic?, medium-hard,thick-bedded, silty, brownish-black (WYR 2/2).

20-_------- Mudstone: phosphatic, medium-hard,thick-bedded, dark-gray (N 3); phos phate, finely pelletal.

19--------- Phosphorite: medium-hard, thin-bed ded, coarsely pelletal, medium-gray (JV5).

18--_----__ Mudstone: medium-hard, thick-bed ded, silty, mo derate-yellowish-brown (10 YR 5/4).

Lower tongue of Shedhorn Sandstone: Ls-17_ -------- Sandstone: medium-hard, thick

bedded, medium-grained, moderate- brown (SYR 4/4); arbitrary basal contact.

16_ _-_-__-_ Sandstone: medium-hard, thick- bedded, medium-grained, light- brown (5YR 5/6); arbitrary basal contact; contains abundant col umns of medium-light-gray (N 6) quartizite, 0.1-0.3 ft in diameter and as much as 5 ft or more long; columns more phosphatic than matrix.

15___-_-___ Sandstone: like bed Ls-16-_-______--14__-__-_-_ Sandstone: like bed Ls 16___________13-_------- Sandstone: like bed Ls-16______-__-_12_-____-_- Sandstone: like bed Ls-16.______-__-ll___--____ Sandstone: like bed Ls-16, but med

ium- to coarse-grained and light- brownish-gray (5YR 6/2).

10- ________ Sandstone: soft, massive, medium-tovery coarse-grained, moderate-brown (5 YR 4/4); contains shell fragments and considerable amount of medium to coarsely oolitic phosphate; arbi trary basal contact.

9_________ Sandstone: soft, massive, medium- tovery coarse grained, pale-red (10.R 6/2); contains shell fragments and nodular masses of medium-grained light-brownish-gray (SYR 6/1) quartzite. Irregular basal contact; scattered small pebbles near base.

8_ ________ Chert and sandstone: sandy, hard,thin- to thick-bedded light-brownish- gray (5YR 5/1) chert containing numerous streaks and lenses of med ium-hard medium-grained dark- yellowish-orange (10 YR 6/6) sand stone as much as 0.6 ft long and 0.3 ft thick.

7-__--__-_ Sandstone: hard, thick-bedded, fine-to medium-grained pale- to light-brown (SYR 5/2- 5/6); contains small pebbles in lower part; contains elongated chert nodules that are as much as 0.6 ft long but are mostly small; irregular basal contact.

Franson Tongue of Park City Formation: F-6--_______ Limestone: sandy, dolomitic, hard,

thin- to thick-bedded, aphanitic, light-brownish-gray (5YR 6/1); sand, fine; finely oolitic phosphatic nodules in upper part.


Thick ness (feet)

. 4

. 8

. 9

1. 1

1. 1

1. 0


(feet)

86. 6

87. 4

88. 3

89. 4

90. 5

91. 5

Uranium

Sample

OAP-468

467

466

465

464

OAP-463

P 205

7. 6

33. 6

7. 5

8.0

29. 3

6. 6

Acid in soluble

53. 5

6. 4

45. 7

51. 5

15. 2

66. 0

Radio- metric ell

0. 003

. 010

. 005

.007

.008

.004

Chemical U

0. 002

. 008

.002

.003

.006

. 002

2. 8 94. 3

5. 0 99. 3

4. 2 103. 55. 0 108. 55. 0 113. 52. 6 116. 15. 0 121. 1

1. 1 122. 2

3. 9 126. 1

4. 0 130. 1

1. 2 131. 3

3. 0 134. 3

FSH-462 2. 8 90. 7 .001 .001

461 2. 1 92. 9 001 . 001

460459458457456

455

1. 71. 71.72. 12. 2

7. 6

92. 691. 892. 791. 090. 7

74. 2

. 001

.0005

.001

. 001

.0005

. 002

. 0005

.0005

. 0005

.001. 001

. 0005

454

453

452

451

2. 4

1. 6

83. 8 . 0005

80. 3 . 0005

001

001

2.0 89. 0 . 0005 001

1. 7 36. 0 . 0005 0005



F-5_

4_

Ls-2.

Description


Limestone: muddy, hard, thin- to thick-bedded, finely to very coarsely crystalline, very light gray (N 8).

Limestone: sandy, medium-hard, thin- to thick-bedded, dark-yellowish- orange (10 YR 6/6); sand, fine to coarse.

Limestone: medium-hard, thin-bedded to massive, medium to very coarsely crystalline, pinkish-gray (SYR 8/1); locally sandy, locally porous.

Sandstone: hard, fissile to thin-bedded, fine- to coarse-grained.

Limestone: sandy, hard, fissile to thick- bedded, dense, grayish-orange (10 YR 7/4); sand very fine. Under lying rocks covered by snow at time section was measured.



2. 5 136. 8 >

Uranium

Acid in- Radlo- metric e~U

Chemical U

1. 0 137. 8

5. 0 142. 8

2. 8 145. 6 ^

2. 0 147. 6

FSH-450 0. 2

449 . 0

32. 2 0. 0005 0. 001

16. 3 . 0005 . 0005

448 . 1 62. 5 .001 . 0005

Centennial No. 3, Mont., lot 1254[Grandeur Tongue of Park City Formation and lower part of Meade Peak Phosphatic Shale Member of Phosphoria Formation measured from hand trench at crest of Cen

tennial Mountains in SE. cor. sec. 1, T. 15 S., R. 1 W., Beaverhead County, Mont., by F. S. Honkala and O. A. Payne and sampled by J. A. Kelleher and R. L. Koni- zeski, in July 1948. Beds strike N. 80° W. and dip 10° SW. Descriptions based entirely on field notes and analytical data. Analyzed for P2Os and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Qeol. Survey]



Bed Description (feet) (feet) Sample

Meade Peak Phosphatic Shale Member ofPhosphoria Formation, lower part:

M-15_ __.--___ Chert: hard, thick-bedded, mottled 1.0 1.0 OAP-541white and medium-light-gray (N 6).The bed is on crest of ridge; upperhalf of Meade Peak member eroded.

14_________ Phosphorite: muddy, soft to medium- 1.7 2.7 506hard, thin-bedded, coarsely ooliticto pisolitic, medium-gray (N 5);lower part softer.

13_ ________ Phosphorite: hard, thin- to thick- 4.6 7.3 505bedded, coarsely oolitic to pisolitic,medium-gray (N 5); contains shellfragments.

12_________ Conglomerate: calcareous, hard, very .2 7.5light gray (N 8); probably phos-phatic. 504

Grandeur Tongue of Park City Formation: G-ll__________ Limestone: sandy, hard, thick-bedded, 2.5 10.0

very light gray (N 8); contains smalllimonitic stains; arbitrary basalcontact.

10__________ Limestone: very sandy, hard, thin- 4.8 14.8 503bedded to massive, finely crystalline,very light gray (N 8); contains smalllimonitic concretions; arbitrary basalcontact.

9__________ Limestone: sandy, medium-hard, thick- 1. 6 16. 4bedded, finely crystalline, very paleorange (lOYfl 8/2); contains" much FSH-502fine to coarse sand.

8__________ Sandstone: calcareous, medium-hard, 3.4thin-bedded, fine- to medium-grained,weak-yellowish-orange (10 YR 7/6);arbitrary basal contact.

Uranium

P205

0.4

Acid in soluble

Radio- metric e~U

Chemical U

93. 2 0. 0005 0. 0005

32.4

2. 7

1. 5

34. 1

8.4

47. 2

60. 3

005

013

001

001

001

008

Oil

002

000

0005



Bed

G-7_.

6..

Q-i-

Description


Sandstone: calcareous, soft, thin- bedded, fine- to coarse-grained, light- yellowish-brown (2.5F6/4).

Sandstone: calcareous, medium-hard, thin-bedded, fine- to medium-grained, very pale brown (IOYR 7/3); arbi trary basal contact.

Sandstone: calcareous, soft, fissile, fine- to medium-grained, weak-yellowish- orange (IOYR 7/6).

Limestone: sandy, medium-hard, thick- bedded, dense, very pale brown (IOYR 7/3); sand, fine to medium.

Sandstone: calcareous, medium-hard, thin-bedded, fine- to very coarse grained, moderate-yellowish-brown (1QYR5/G).

Conglomerate: calcareous, hard, thick- bedded, light-brownish-gray (10 YR 6/1); grain size ranges from medium- sand size to 0.2 ft; pebbles, composed chiefly of chert but also of limestone and sandstone, are poorly rounded and sorted; stringers penetrate 0.2- 0.6 ft into cracks in underlying bed, contact generally irregular.

Quadrant Formation, top bed:Sandstone: calcareous, medium-hard,

fissile to massive, medium- to very coarse-grained, very pale brown (IOYR 7/3).


Thick ness (feet)

Cumulativithickness

(feet)

Uranium

3. 4 23. 2

1. 6 24. 8

2. 1 36. 5

Sample

FSH-501

500

499

498

Acid in- Radio- Chemical P2OS soluble metric eV U

0. 1 68. 6 0. 001 0. 0005

4 68. 7 . 001 . 0005

0 64. 5 . 002 . 0005

2 56. 0 . 005 . 0005

4. 4 4. 4 497 .3 61. 0 . 0005 . 000

Centennial No. 2, Idaho, lot 1255

[Shedhorn Sandstone and Tosi Chert and Retort Phosphatic Shale Members of Phosphoria Formation measured from hand trench near crest of Centennial Mountains N W. of center of sec. 12, T. 14 N., R. 40 E., Clark County, Idaho, by F. S. Honkala and O. A. Payne and sampled by J. A. Kelleher and R. L. Konizeski, in July 1948. Beds strike N. 65 W. and dip 14° S W. Descriptions based entirely on field notes and analytical data. Analyzed for P2O5 and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]

Chemical analyses (percerd)

Bed

Cumulativethickness

(feet)

Uranium

SampleAcid Radio-

metric e

D-41.

40_

39.

38.

37_

36.

35.

34.

33_

Thickness Description (feet)

Dinwoody Formation, lower part:Mudstone: medium-hard, thin-bedded, strong- 0.5 0.5 __________ ______ ______ _______

yellowish-brown (10 YR 5/8); contains fine- tomedium-grained sand.

Mudstone and limestone: 0.2 ft muddy hard .8 1. 3 FSH-540 0. 65 77. 5 0. 001dense light-gray (N 7) limestone underlain by0.6 ft of medium-hard thin-bedded grayish- brown (10 YR 4/2) mudstone.

Mudstone: medium-hard, hssile to thin-bedded, 5.0 6.3 539 1.0 81. .001light-olive-gray (5Y 5/2); arbitrary basalcontact.

Mudstone: medium-hard, fissile to thin-bedded, 1. 3 7. 6grayish-brown (10 YR 4/2).

Limestone: bard, thin-bedded, finely crystal- .3 7. 9line, light-brownish-gray (SYR 6/1).

Mudstone: medium-hard, fissile to thin-bedded, .7 8. 6grayish brown (10 YR 4/2). } 538 1.1 81.5 .001

Mudstone: carbonatic, medium hard, strong- .5 9. 1yellowish-brown (10 YR 5/8).

Mudstone: medium-hard, fissile to thin-bedded, 2. 2 11. 3grayish-brown (IOYR 4/2); arbitrary basalcontact.

Mudstone: medium-hard, fissile to thin-bedded, 5. 0 16. 3 537 1. 2 74. 4 . 001grayish-brown (10 YR 4/2).


Centennial No. 2, Idaho, lot 1255 Continued

Bed Description

Dinwoody Formation, lower part Continued D-32 ________ Conglomerate: hard, medium-gray (N 5) to

light-brown (5YR 5/6); pebbles, as much as 2 cm in diameter; contains apatite pellets and numerous fossils (shark teeth, pelecypods, and others).

Tosi Chert Member of Phosphoria Formation:To-31_-______- Chert: hard, moderate-brown (5YR 3/4); arbi

trary basal contact.30___--__-- Chert: hard, thin-bedded, brownish-gray (10 YR

4/1); arbitrary basal contact.29__--_____ Chert: hard, thin- to thick-bedded, dark-gray

(N 3); contains some finely sandy mudstone stringers; arbitrary basal contact.

28-_-___--- Chert: hard, fissile to thin-bedded, dark-gray (N 3); contains a few mudstone partings; arbitrary basal contact.

27__------- Chert: like bed To-28; arbitrary basal contact.26_________ Chert: like bed To-28; arbitrary basal contact-25____-___- Chert and mudstone, interbedded: alternating

hard fissile to thin-bedded pale-brown (\OYR 6/2) chert (75 percent) and medium-hard fissile brownish-gray (IOYR 4/1) mudstone.

Retort Phosphatic Shale Member of PhosphoriaFormation:

Rt-24_________ Mudstone and chert: hard fissile to thin-beddedbrownish-gray (IOYR 4/1) mudstone consti tutes most of unit and grades upward into chert; arbitrary basal contact.

23___--__-_ Mudstone: hard, fissile to thin-bedded, brownish- gray (IOYR 4/1) to light-brownish-gray (10 YR 5/1).

22_________ Mudstone: medium-hard, thin-bedded, alter nating brownish-gray bands (IOYR 3/1 and 4/1); contains medium sand.

21 _________ Mudstone: medium-hard laminated to thin- bedded, brownish-black (IOYR 2/1), contains very thin medium- to light-gray layers; con tains medium sand; arbitrary basal contact.

20__------- Mudstone: medium-hard, thin-bedded, brown ish-gray (IOYR 3/1); contains medium sand; small offset and drag along cross-cutting shear.

19_-_-----_ Mudstone: hard, fissile to thin-bedded, brown ish-gray (IOYR 3/1); top 0.5 ft soft and brecciated, pale-brown (IOYR 5/3).

18----_--_- Mudstone: hard, thin- to thick-bedded, dark- gray (N 3)

17---__-__- Mudstone: hard, fissile to thick-bedded, gray ish-black (N 2).

16_--_---_- Phosphorite: medium-hard, thin-bedded, coarsely pelletal, medium-gray (N 5).

15---__---- Mudstone: medium-hard, fissile to thin-bedded, dark-gray (AT" 3).

14_________ Mudstone: soft, thick-bedded, pale-brown(10 YR 5/2); basal 0.2 ft fissile, medium-dark- gray (N 4).

13_________ Phosphorite and mudstone, interlaminated: al ternating bands of muddy medium-hard thin- to thick-bedded medium coarsely pelletal medium-dark-gray (N 4) phosphorite (80 percent (and phosphatie brownish-gray (IOYR 3/1) mudstone.

12_ ________ Phosphorite: medium-hard, thin- to thick- bedded, medium coarsely pelletal, medium- dark-gray (N 4).

!!_________ Mudstone: medium-hard, thick-bedded, gray ish-brown (lOl^R 4/2) to moderate-yellowish- brown (IOYR 4/4).

10.________ Phosphorite: muddy, medium-hard, thin- tothick-bedded, coarsely pelletal, medium-light- gray




(feet) (feet)

1. 3

3.8 2. 7 4. 0

4. 4

8. 210.914.9

1. 8 16. 7

1. 7 18. 4

.9 __---_

1. 6 20. 9

3. 0 23. 9

3. 2 27. 1

Sample

Uranium

Acid Radio- insoluble metric e~U

. D

.3

. 6

2. 2

ID. y

.3

FSN-536

.9 535

3. 1 534

1.3

. 4

. 4

89.0

93. 0

92. 5

0. 0005

.0005

.0005

533

532531530

529

87.4

89. 590. 290. 1

525

524 80. 3

. 0005

. 0005

.0005

. 0005

. 65 81. 6 . 001

528 . 80 82. 4 . 001

OAP-527 .8 86. 5 . 001

526 1. 0 81. 5 . 002

1. 05 80. 7 . 002

. 002

2. 2

5.0

1. 5

. 7

. 7

.7

. 7

1. 7

. 9

29. 3 523

34. 3 522

35. 8 521

36. 5 520

37. 2 <

37.9

38. 6

519

518

40. 3 517

41. 2 516

1. 1

1. 7

31.4

5.4

9. 65

34. 5

2. 8

19. 8

77. 1

70. 6

10. 0

66. 0

52. 3

4. 3

74. 4

35. 2

.002

. 003

1 . Oil

. 005

. 006

. 008

. 003

. 009


Centennial No. 2, Idaho, lot 1255 Continued

Bed

Ls-9.

8.

7.

6-

Description

Lower tongue of Shedhorn Sandstone; base not exposed:

Sandstone: hard, thick-bedded, light-gray (N 7); contains shell fragments.

Sandstone: hard, thick-bedded to massive, pale- brown (10FR 6/2); contains shell fragments.

Sandstone: hard, massive, light-gray (N 7); contains considerable amounts of calcite.

Sandstone: hard, massive, light-olive-gray (5F 6/1); contains sandstone columns 0.1-0.3 ft across and as much as 5 ft long, nearly normal to bedding; arbitrary basal contact.

Sandstone: like bed Ls-6; locally gritty. ______Sandstone: hard, massive, yellowish-gray (5F

7/2); contains considerable amounts of phos phate and contains fossils in lower 0.5 ft.

Sandstone: hard, massive, medium-grained, light-gray (N 7); contains shell fragments and sandstone columns 0.1-0.3 ft diameter and as much as 5 ft long, nearly normal to bedding.

Sandstone: phosphatic, hard, thick-bedded, medium-grained, pale-brown (10 FR 6/2); apatite medium coarsely oolitic; contains shell fragments; gradational basal contact.

Sandstone: calcareous, hard, massive, coarse grained, light-gray (N 7); contains consider able amounts of phosphate and shell frag ments. Underlying beds covered.

Thickness (feet)

Cumulativethickness

(feet) Sample

1. 6 42. 8 FSH-5I5

3. 0 45. 8 514

2. 6 48. 4 513

5. 0 53.4 512

5. 0 58. 42. 1 60. 5

5. 0 65. 5

1. 1 66. 6

4. 3 70. 9

511510

509

508

507


Uranium

Acid Radio- PsOj insoluble metric eU

3. 2 87. 1 0. 001

1. 7 92. 9 0005

1. 3 76. 2 . 0005

1. 7 85. 7 . 0005

2. 8 85. 3 . 0015. 0 80. 2 . 002

3. 7 77. 0 . 001

12. 8 52. 6 . 007

7. 5 45. 2 . 004

Chemical II, 0.009 percent.

Cedar Creek, Mont., lot 1256[Retort Phosphatic Shale Member of Phosphoria Formation measured in bulldozer trench near Cedar Creek, sec. 26, T. 9 S., R. 11 W., Beaverhead County, Mont., on east

limb of syncline. Beds strike north and dip 61° W. Measured by E. T. Ruppel and sampled by J. A. Kelleher, in August 1948. Analyzed for PzOs and acid insolu ble by U.S. Bur. of Mines, and for uranium by U.S. Geol. Survey]


Bed

To-59-

Rt-58-

57-

56_

55_

54.

53.

52_

51.

50.

49.

Description

Tosi Chert Member of Phosphoria Forma tion, basal bed:

Chert: hard, grayish-brown (7. 5 KB4/2), thick-bedded.


Mudstone: medium-hard, very palebrown (10 YR 7/3), thin-bedded.Fossil-colln. No. 10829.

Mudstone: medium-hard, very palebrown (WYR 7/3), thick-bedded.

Phosphorite: cherty(?),hard, dark-gray(N 3), thick-bedded.

Limestone: sandy, phosphatic, soft,weak - yellowish - orange, thick-bedded; sand is very fine; apatite isvery finely pelletal.

Mudstone: soft, light- yellowish-brown(10 YR 6/4), very thick bedded.

Mudstone: calcareous, phosphatic,soft, very pale brown (10 YR 7/3),thick-bedded; apatite is finely pelletal.

Mudstone: soft, pale-orange (7.5YR8/4), very thick bedded.

Mudstone: soft, dark-yellowish-orange(10FR 6/8), thick-bedded.

Phosphorite: muddy, soft, pale-brown(7.5YR 6/2), thin-bedded, coarselypelletal.

Mudstone: soft, weak-yellowish-orange(10 YR 7/6), thick-bedded.

Thick ness (feet)

5. 0

11. 5

10. 0

. 8

. 3

1. 5

. 3

3. 0

. 3

. 1

. 6

Cumu lative

thickness (feet)

5.0

16. 5

26. 5

27.3

27. 6

29. 1

29. 4

32. 4

32. 7

32. 8

33. 4

Uranium

Sample

ETR-585

584

583

582

581

580

579

K78

P 205

2. 3

1.0

1. 1

15. 4

11.4

4. 6

9.2

2. 0

Acid insoluble

78. 5

74.0

82. 3

34. 2

22. 7

62. 6

42. 2

77. 6

Radio- metric

eU

0. 0005

.001

. 001

.007

. 005

.004

. 005

. 004

Chemical U

.005

. 005

. 004

577 9. 6 51.0 006 .004


Cedar Creek, Mont., lot 1256 Continued

471

Rt-48_

47.

46_

45_

44.

43.

42_

41-

40-

39-

38.

37.

36_

35_

34_

33-

32-

31-

30.

29-

28.

27.


Description

Retort Phosphatic Shale Member of Phos- phoria Formation Continued

Mudstone: medium-hard, pale-brown (7.5YR 6/2), thick-bedded.

Dolomite: phosphatic(?), soft, light-yel lowish-brown (10 YR 6/4), fissile.

Mudstone: medium-hard, pale-brown (7.5YR 6/2), thin-bedded; grades from bed below.

Limestone: muddy, medium-hard, yel lowish-gray (10 YR 8/1), thin-bedded.

Mudstone: soft, laminated yellowish- white (2.5Y 9/2) and grayish-brown (7.5YR 4/2), fissile.

Phosphorite: carbonatic, medium-hard, very pale brown (10 YR 7/3), thin- bedded, medium-pelletal.

Carbonate rock: phosphatic, medium- hard, very pale orange (10 YR 8/2), thick-bedded; apatite is medium pelletal.

Phosphorite: dolomitic, hard, medium- gray (N 6), thick-bedded, nodular and coarsely pelletal; nodules are as much as 50 mm in diameter.

Mudstone: medium-hard, weak-yel lowish-orange (10 YR 7/6), thick- bedded.

Phosphorite: muddy, soft, very pale brown (10 YR 7/3), thin-bedded, nodular; nodules are as much as 70 mm in diameter.

Phosphorite: hard, medium-gray (N 5), thick-bedded, medium-pelletal; contains many phosphatic brachiopod shells. (Analysis in error.)

Phosphorite: muddy, medium-hard, light-brown (7.5 YR 6/4), thick- bedded, finely pelletal. Fossil-colln. No. 10828.

Mudstone: soft, light-brown (7.5YR 5/6), fissile.

Phosphorite: medium-hard, light-yel lowish-brown (10 YR 6/4), thin-bed ded, finely pelletal.

Phosphorite: muddy, soft, light-brown (7.5YR 6/4), thick-bedded, nodular; nodules are as much as 60 mm in diameter.

Phosphorite: argillaceous, hard, pale- brown (IQYR 6/2), thick-bedded, finely pelletal.

Mudstone: soft, weak-yellowish-orange (IQYR 8/4), thick-bedded.

Mudstone: phosphatic, soft, very pale brown (10 YR 7/3), thick-bedded; apatite is finely pelletal; grades from bed below.

Mudstone: phosphatic, soft, weak- yellowish-orange (10 YR 7/6), fissile; apatite is nodular.

Phosphorite: muddy, medium-hard, light-gray (N 7), thin-bedded, finely pelletal.

Mudstone: phosphatic, carbonatic, soft, light-brown (7.5 YR 6/4), fis sile; apatite is finely pelletal.

Phosphorite: hard, yellowish-gray (IQYR 7/1), thin-bedded, finely pelletal.


(feet) (feet) Sample Pz05Acid

insoluble

Uranium

ffadiometric ChemicaleTJ U

0.2

. 4

. 2

1.2

1. 2

.4

. 6

33. 6 >

04 nOTC. \J

34. 2

OC A DO. Tt

36. 6

37.0 '

37. 6

ETR-576 6.3 42.8 0.004 _______

575 1.8 48.3 .001 _______

574 7. 6 12. 7 005 0. 003

573 17. 4 19. 6 . 005 . 004

0. 2

. 1

. 2

38.4

39. 3

39. 5

40. 2

40. 5

41. 2

41.3

42. 0

42.5

43.0

43.4

43. 6

43.7

43.9

572

571

570

569

568

567

566

565

564

563

562

561

560

21. 0

1. 4

18.9

32.6

23. 5

5.7

20.9

17.5

22. 1

3.5

2.6

72. 0

33. 5

25. 0

64.7

33. 0

24. 3

39. 1

41. 4

58.3

20.3

004

, 003

004

006

006

, 004

. 006

.005

007

.003

, 004

. 004

. 0006

. 006

. 004

. 005

. 005

. 006

0. 005


Cedar Creek, Mont., lot 1256 ContinuedChemical analyses (percent)

Bed Descriptirn


Rt-26-________ Phosphorite: argillaceous, medium- hard, light-gray (N 7), fissile, medium-pelletal. Fossile-colln. No. 10827.

25_________ Phosphorite: hard, medium-gray (N6), thick-bedded, nodular and medium-pelletal; nodules are as much as 160 mm in diameter.

24_________ Mudstone: medium-hard, light-brown(7.5 YR 6/4), fissile.

23_________ Phosphorite: calcareous, hard, me dium-gray (N 6), thick-bedded, nodular and finely pelletal; nodules are as much as 150 mm in diameter.

22_________ Mudstone: phosphatic, soft, weak- orange (7.SYR 7/6), thick-bedded; apatite is nodular.

21_________ Dolomite: muddy, medium-hard, weak- yellowish-orange (WYR 7/6), thick- bedded, aphanitic.

20_________ Dolomite: muddy, phosphatic, me dium-hard, light-brown (7.SYR 6/4), thick-bedded, aphanitic; apatite is finely pelletal.

19_________ Phosphorite: hard, very pale brown(10 YR 7/2), thick-bedded, nodular and medium-pelletal; nodules are as much as 50 mm in diameter; grades from bed below.

18_________ Mudstone: phosphatic, soft, light- brown (7.SYR 6/4), fissile; apatite is nodular and pelletal; grades from bed below. Fossil-colln. No. 10826.

17_________ Mudstone: phosphatic, soft, light- brown (7.SYR 6/4), fissile; apatite is finely pelletal; grades from bed below.

16_________ Phosphorite: dolomite, soft, very palebrown (10 YR 7/2), thin-bedded, medium-pelletal.

15_________ Mudstone: soft, light-brown (7.5 YR5/6), thin-bedded.

14__ _______ Mudstone: phosphatic, soft, light- yellowish-brown (10 YR 6/4), thin- bedded; apatite is medium pelletal.

13_________ Phosphorite: carbonatic, medium-hard,light-brownish-gray (10 YR 5/1), thick-bedded, nodular and medium- pelletal; nodules are as much as 80 mm in diameter.

12_________ Mudstone: phosphatic, soft, very palebrown (10 YR 7/3), thin-bedded; apatite is finely pelletal; grades from bed below.

!!_________ Mudstone: soft, very pale brown (10 YR7/3), thin-bedded. Fossil-colln. No. 10825.

10-________ Phosphorite: medium-hard, light-gray(N 7), thin-bedded, finely pelletal; contains a few apatite nodules as much as 20 mm in diameter.

9_________ Phosphorite: hard, light-brownish-gray(10 YR 6/1), thin-bedded, medium- pelletal.

8_________ Phosphorite: argillaceous, medium- hard, very pale brown (10 YR 7/2), thin-bedded, finely pelletal.

7_-_______ Mudstone: carbonatic, medium-hard,weak-yellowish-orange (10 YR 8/4), thin-bedded.


(feet) (feet)

0. 6 44. 5

.4 44. 9

.2 45. 1

.3 45. 4

.3 45. 7

.6 46. 3

.3 46. 6

.3 46. 9

.3 47. 2

6 48.4

1 48. 5

2 48. 7

4 49. 1

,3 49. 4

1 49. 5

,1 49. 6

,1 49. 7

.2 49. 9

.6 50. 5

Sample

ETR-559

Uranium

Acid Padiometric Chemical ivsoluble eU TJ

22. 8 27. 0 0. 007 0. 006

558

557

556

555

554

553

20. 3 26. 6 005 . 004

10. 1 55. 0 . 004

2.9 58. 9 002

25. 1 17. 6 . 006 . 005

9.9 56. 1 005 . 003

12. 4 52. 1 005 . 003

-552

551

550

16. 8 3. 8 . 006 . 004

20. 8 17. 7 005 . 005

14. 1 46. 5 . 006 . 004

549

548

547

19. 7 30. 2 . 005 . 004

21. 5 30. 6 006 . 004

6. 6 49. 8 003 ____---


Cedar Creek, Mont., lot 1256 ContinuedChemical analyses (percent)

Uranium

Bed

Rt-6.

5-

4_

3.

2.

1.

Description

Retort Phosphatic Shale Member of Phos phoria Formation Continued

Mudstone: soft, weak-yellowish-orange (10 YR 7/6), thick-bedded; grades from bed below.

Mudstone: soft, laminated light-gray (N 8) and weak-yellowish-orange (10KR 7/6), fissile.

Phosphorite: muddy, soft, light-gray (N 7), thin-bedded, finely pelletal.

Phosphorite: muddy, soft, laminated weak-yellowish-orange (10 YR 7/6) and light-gray (AT 8), fissile, medium- pelletal.

Mudstone: phosphatic, soft, weak- yellowish-orange, fissile; apatie is nodular.

Phosphorite: sandy, hard, grayish- brown (10F.K 4/2), very finely pelletal; underlying bed not de scribed. Fossil-colln. No. 10824.


(feet) (fee) Sample

0. 5 51. 0 ETR-546

.6 51. 6 545

Acid Radio metric Chemical insoluble e\J U

1.7 79.4 0.003 _______

6. 7 62. 0 . 005 0. 003

.1 51. 7

1. 0 52. 7

.4 53. 1

3. 0 56. 1

544

543

542

16. 5 40. 3 005 . 004

8.2 51.1 .002 --_-___

26. 3 28. 6 . 007 . 006

Cave Creek, Mont., lot 1257[Parts of Phosphoria and Shedhorn Formations measured on south side of Cave Creek, NWHNWW sec. 10, T. 6 S., R. 10 W., Beaverhead County, Mont., about 2,000 ft

west of axis of northeastward-plunging Cave Creek syncline. Beds strike N. 25° W. and dip 40° NE. Beds To-48 to Us-54 are poorly exposed, and descriptions are based largely on float; beds Rt-4 to Rt-45 were described in bulldo'er trench. Measured by E. T. Ruppel and sampled by J. A. Kelleher, in August 1948. Analyzed for P2Os and acid insoluble by U.S. Bur. of Mines and for other constituents by U.S. Geol. Survey]


Bed Description

Upper tongue of Shedhorn Sandstone;contains beds of intertonguing TosiChert Member of Phosphoria Formation:

Us-54_________ Quartzite: gray_-__-______-_---___.53_________ Chert and quartzite_________________ 16.052_________ Do-__--_-__-_-_-____-__-____.

50_________ Do-_--___-_-----____---__III_Tosi Chert Tongue of Phosphoria Forma

tion :

48_____-___ Chert: black to ~tan-----__I__-_IIIIL 32.547_________ Chert: hard, dark-gray (N 3), thick-

bedded. (46)_________ Rhyolite(?) sill ranging from 4.5 to 6 (5. 25)?

ft in thickness separates beds Rt-45 and To-47.


Rt-45-___--___ Phosphorite: hard, dark-gray (N 3), thick-bedded, medium-pelletal.

44_________ Phosphorite: argillaceous, hard, dark- gray (N 4), thick-bedded. 1

(43)-_---__- Rhyoiite(?) sill, 1.2 ft thick, separates (1. 2)? beds Rt-42 and Rt-44.

42_________ Mudstone: phosphatic, medium-hard,weak-yellowish-orange (10 YR 7/6), thin-bedded; apatite is finely pel letal. 2

41 _________ Mudstone: medium-hard, light-brown(7.SYR 6/4), thick-bedded.

40_________ Mudstone: soft, light-gray (A 7), thin- bedded.

39_________ Chert: phosphatic, soft, medium-gray(N 6), thick-bedded; apatite is finely pelletal.

38_________ Mudstone: soft, yellowish-gray (2.5F7/2), thick-bedded.


Uranium

Thick- C ness (jeet)

11.0 16.0 11.0 20.0 22. 0

28. 0 32. 5

3. 5

(5. 25)?

. 6

. 8

(1. 2)?

1. 4

1. 1

3.0

1. 3

thickness (feet)

11. 0 27.0 38.058.0 80.0

108.0 140. 5 144. 0

145. 6

147. 4

148. 8

149. 9

152. 9

154. 2 1

Labora- Acid metric Field tory P.Os insoluble e~U

TTTTJ ftOn QOTC Q 1 CQ C (\ (\C\~\

619 2977 . 9 92. 4 . 003

618 2976 30. 4 18. 9 . 006

617 ---_ 29.4 21.5 .005

616 ---_ 3.7 71.5 .003

615 ____ 9. 7 58. 7 .005

614 ____ 1.4 76.8 .004

613 ____ 5.6 64.4 .005

Chemical U

0. 005

.005

. 005

. 003

612 8. 5 62. 2 005 .0036


Cave Creek, Mont., lot 1257 Continued

Bed Description


Rt-(37) _______ Lens like bodies of rhyolite(?) as muchas 2.3 ft thick have been intruded between beds Rt-35 and Rt-38.

36_________ Mudstone: soft, light-gray (NT).....35_ ________ Phosphorite: soft, yellowish-gray (2.5 Y

7/2), thick-bedded, medium-pelletal; contains a few apatite nodules as much as 60 mm in diameter.

34________- Mudstone: phosphatic, soft, yellowish- gray (10 YR 7/1), thin-bedded; apa tite is finely pelletal; contains a few apatite nodules as much as 30 mm in diameter.

33 _______ Phosphorite: argillaceous, medium-hard, yellowish-gray (2.5F7/2), thin- bedded, medium-pelletal.

32_________ Mudstone: phosphatic, medium-hard,yellowish-gray (2.5 Y 7/2), thin- bedded; apatite is finely pelletal and is concentrated into poorly defined laminae.

31--------- Mudstone: phosphatic, medium-hard,light-gray (N 8), thick-bedded; apa tite is medium pelletal.

30_------__ Phosphorite: soft, weak-yellowish- orange (2.5 Y 8/4), thick-bedded; medium-pelletal. Possil-colln. No. 10836.

29___------ Mudstone: soft,weak-yellowish-orange(2.5 Y 7/4), thin-bedded.

28__---_-__ Mudstone: phosphatic, soft, light-gray (N 7), thick-bedded; apatite is finely pelletal.

27-------_- Mudstone: soft,light-gray (N7), thick- bedded. (Analysis may be in error.)

26_-__ --_- Phosphorite: argillaceous, soft, yel lowish-gray (10Y72 8/1), thin-bedded, medium-pelletal.

25__---_-__ Phosphorite: medium-hard, yellowish- gray (2.5 Y 7/2), thick-bedded, finely pelletal; contains a few apatite nod ules as much as 60 mm in diameter.

24.________ Mudstone: phosphatic,soft.pale-brown(10YR 6/2), fissile; fine-grained apa tite pellets are concentrated in lami nae.

23 _________ Phosphorite: argillaceous, medium- hard, light-gray (N7), thick-bedded, finally pelletal; grades from bed be low.

22_--__--__ Mudstone: phosphatic, medium-hard, light-yellowish-brown (WYR 6/4), thick-bedded; apatite is very finely pelletal; contains a few apatite nodules as much as 45 mm in diameter.

21_________ Mudstone: soft, weak-yellowish-orange(10 YR 7/6), thin-bedded.

20_--_____- Mudstone: phosphatic, soft, very pale orange (IOYR 8/2); apatite is finely pelletal.

Thick- Cumulative ness thickness(feet) (feet)

(2. 3)?

4. 6 59. 4. 8 160. 2

. 5 160. 7

. 5 161. 2

. 8 162. 0

. 4 162. 4

. 4 162. 8

. 3 163. 1

. 4 163. 5

. 4 163. 9

. 9 164. 8

. 8 165. 6

. 2 165. 8

. 4 166. 2

. 7 166. 9

. 5 167. 4

. 3 167. 7

Sample number


Uranium

Radio-Labora- Add metric Chemical

Field tory P2O5 insoluble e~U U

ETR-611

610

1.8 76. 8 0.012 0.002

. 5 79. 5 . 003609 ____ 32. 85 9.6 .007 .007

608 _-__ 15.85 43.5 .006 .003

607 _ _ _ _ 22. 1 33. 0 . 006 . 004

606 _ _ _ - 6. 7 66. 3 . 005 . 002

605 _ _ _ _ 23. 6 29. 0 . 007 . 005

604 __-_ 14.4 49.8 .005 .004

603 ---- 24. 6 25. 6 .007 .005

602 -___ 30. 7 15.0 .006 .004

601 2959 21. 1 34. 3 . 005 . 004

600 2958 11. 8 57. 0 . 005 . 003

599 2957 9. 4 71. 0 . 003


Cave Creek, Mont., lot 1257 Continued

Bed Description

Thick- Cumulative -ness thickness

(feet) (feet)

Sample number

Chemical analysis (percent)

Uranium

Labora- Field tarry

Padic-Aeid metric Chemical

P2Os insoluble eU U

Retort Phosphatic Shale Member of Phos-pharia Formation Continued

Rt-19_________ Mudstone: phosphatic, medium-hard, 0.6 168.3light-brownish-gray (10 YR 6/1), thin-bedded; apatite is medium pelletal; contains a few apatite nodules as much as 50 mm in diameter. (Analysis may be in error.)

18__---____ Phosphorite: muddy, hard, light-gray .4 168.7(N 7), thin-bedded, medium-pelletal. Fossil-colln. No. 10835.

17-__-_---_ Mudstone: phosphatic, medium-hard, .4 169.1 pale-brown (2.5 Y 5/2), thin-bedded; apatite is finely pelletal; contains a few apatite nodules as much as 60 mm in diameter.

16-_-_-____ Mudstone: phosphatic, medium-hard, . 4 169. 5very pale brown (10 YR 7/2), thick- bedded ; apatite is finely pelletal.

15__-_--___ Phosphorite: muddy, soft, light-gray . 2 169. 7 (N 8), thin-bedded, finely pelletal. Fossil-colln. No. 10834.

14_________ Mudstone: phosphatic, medium-hard, .4 170.1very pale brown (10F.R 7/2), thin- bedded; apatite is finely pelletal.

13_____-__- Mudstone: phosphatic, soft, light-gray . 9 171. 0(N 8); apatite is finely pelletal. Fossil-colln. No. 10833.

12___-----_ Phosphorite: muddy, medium-hard, 1.6 172. 6light-gray (N 8), thin-bedded, finely pelletal.

!!___--____ Phosphorite: muddy, soft, moderate- . 1 172. 7yellowish-brown (10 YR 5/6), fissile, finely pelletal.

10_________ Mudstone: phosphatic, soft, yellowish- . 6 173. 3gray (2.5 Y 7/2),) thin-bedded; apa tite is finely pelletal. Fossil-colln. No. 10832.

9_--______ Mudstone: soft, yellowish-gray (2.5F 1.4 174.77/2, thick-bedded.

8___-_-___ Mudstone: soft, light-brown (7.5YR .2 174.95/6, thin-bedded.

7_________ Mudstone: phosphatic, soft, yellowish- 1.3 176.2gray (2.5 Y 7/2), thin-bedded; apatite is finely pelletal.

6_________ Mudstone: soft, yellowish-gray (2.5F7/2), thin-bedded; contains a few apatite nodules as much as 130 mm in diameter.

5_ ________ Phosphorite: muddy, medium-hard, .3 177.2dark-gray (./V4), thin-bedded, nodu lar and finely pelletal; nodules are as much as 50 mm in diameter.

4_________ Phosphorite: sandy, soft, yellowish- .9 178.1gray (2.5F/72), thin-bedded; grades from bed below.

3_________ Sandstone: phosphatic, yellowish-gray 2.2 180.3(10 YR 7/1), thick-bedded, medium- grained; irregular contact with bed below.

_________ Similar to bed Rt-3-------_--------- .4 180.7Franson Tongue of Park City Formation,

uppermost bed: -------__ Sandstone: cherty(?)-_-----_------__- .9 181.63, 1.6 percent; Fe2Os, 1.24 percent; loss on ignition, 2.25 percent. 3, 1.8 percent; Fe2Os, 1.00 percent; loss on ignition, 2.18 percent.

ETR-598 2956 2. 0 59. 5 0. 005 0. 003

597 2955 24. 5 25. 7 . 007 . 006

596 2954 10. 5 57. 8 . 006 . 004

595 2953 18. 7 38. 4 . 008 . 006

594 2952 14. 7 45. 1 . 008 . 005

593 2951 14. 9 44. 4 . 006 . 004

592 2950 18. 4 39. 7 . 007 . 005

591 2949 13. 8 51. 3 . 007 . 005

590 2948 4.8 61.4 .004 ____

589 2947 13. 6 44. 6 . 005 . 003

5882946 6.4 62.3 .004 ____

587 2945 29.4 21.6 .004 _______

586 2944 20. 2 45. 4 . 004


Little Sheep Creek, Mont., lots 1294 and 1295

[Permianrocks measured at Little Sheep Creek, Beaverhead County, Mont, on south end of major anticlinal structure. Beds Q-l to R-65 (lot 1294) measured from bulldozer trench, and beds R-66 to F-79 from natural exposure near Middle Fork of Little Sheep Creek, SWJ-i sec. 34, T. 14 S., R. 9 W. Beds strike N. 50° W. and dip 25° SE. Beds F-80 to To-119 (lot 1295) measured from bulldo-er trench near West Fork of Little Sheep Creek, S J-i sec. 33, T. 14 S., R. 9 W. Beds strike N. 80° E. and dip 10° S. Measured by E. R. Cressman, W. H. Wilson, and C. W. Tandy, and sampled by W. J. Garmoe, B. K. Replogle, R. F. Gosman, and J. L. Elliott, in July 1949. Samples analyzed for PzOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

To-119_.

117.

116.

112.

111.

110.

Cs-109_

Rt-108_

107-

(106).

105_

104. 103 _

102_ 101.

100. 99..

98.

97.

Description

Tosi Chert Member of Phosphoria Forma tion; upper part not exposed:

Chert: muddy, medium-hard, grayish- brown (2.5F 4/2), thin-bedded.

Chert: muddy, medium-hard, pale- brown (2.5F 5/2), thin-bedded.

Chert: muddy, dolomitic, medium- hard, grayish-brown (2.5F 4/2), thick-bedded.

Chert: silty, medium-hard, grayish- brown (2.5F3/2), thin-bedded.

Dolomite: medium-hard, grayish- brown (10 YR 4/2), very thick-bed- ed, aphanitic; pinches out along strike.

Chert: muddy, medium-hard, grayish- brown (2.5F 3/2), thin-bedded; in fault contact with unit below.

Chert: muddy, medium-hard, brown ish-gray (10 YR 3/1), thin-bedded.

Chert: muddy, medium-hard, pale- brown (10 YR 6/2), thin-bedded. Fossil-colln. No. 11663.

Chert: muddy, medium-hard, grayish- brown (2.5 F 3/2), thin-bedded. Fossil-colln. No. 11662.

Chert: muddy, medium-hard, brown ish-gray (10 YR 4/1), thin-bedded. Fossil-colln. No. 11661.

Cherty shale member (?) of Phosphoria For mation:

Mudstone: cherty, medium-hard, pale- brown (2.5 F 4/2), thin-bedded. Fos sil-colln. No. 11660.


Mudstone: medium-hard, black (AT 2), thin-bedded; basal 0.1 ft of bed is crumbly and may be a shear zone. Fossil-colln. No. il659.

Mudstone: medium-hard, black (AT 2), thin-bedded. Fossil-colln. No. 11658.

Covered: (Beds Rt-105 and Rt-107 are separated by a covered interval and by at least one fault of unknown displacement.)

Mudstone: medium-hard, brownish- gray (10 YR 4/1), thin-bedded.

Mudstone: crumbly, black (N 2)_-___Mudstone: soft, dusky-brown (10F.R

2/2), thick-bedded.Mudstone: crumbly, black (N 2)_--__Mudstone: medium-hard, black (N 2),

thin-bedded.Mudstone: crumbly, black (A7 2)_--_-Mudstone and phosphatic mudstone,

inter bedded: soft dusky-brown (WYR 2/2) thin-bedded phosphatic mudstone interbedded with medium- hard black (N 2) thin-bedded mudstone; apatite is finely pelletal; grades from bed below.

Carbonate rock: phosphatic, muddy, crumbly, brownish-gray (10 YR 3/1); apatite is finely pelletal.

Mudstone and phosphorite: bed is faulted and weathered; so, that detailed logging is not possible.


(feet) (feet)

Uranium

SampleAcid Radiometric Chemical

insoluble eU U

7. 1

3. 9

3. 5

4.0

1. 3

14.0

8.0

5. 5

10. 4

15.0

2. 3

5. 3

3.7

1. 1

. 4

. 2

1. 72. 0

7. 1

11.0

14. 5

18. 5

19. 8

38. 6

46. 6

52. 1

62. 5

77. 5

79. 8 ERG-358

85. 1 357

2. 0 53. 6 0. 002

5. 5 46.0 002

2. 0

89. 990.0

90. 490. 6

92. 394. 3

95. 0

97. 0

356 1. 0 84. 5 001

355 1. 3 59. 2 003

354 3. 8 54. 2 004353 6. 7 41. 9 004

352 11.5 20.9 .004

351 10. 7 41. 1 004


Little Sheep Creek, Mont., lots 1294 and 1295 ContinuedChemical analyses (percent)

Bed

Rt-96.

95_

94-

93-

92.

91.

90-

87.

86_

85-

84_

83-

82-

81.

F-80-

79.

78.

77.

76.

75.

98. 5

99. 9



Mudstone: carbonatic, soft, weak-yel- 0. 8 97. 8 ^ lowish-orange (10 F^ 7/6), thick- bedded.

Limestone: phosphatic, medium-hard, .2 98. 0 yellowish-gray (10F.K 7/1), thin- bedded; apatite is very finely pel letal ; bed is locally brecciated and is in fault contact with unit below.

Limestone: muddy, soft, weak-yellow- . 5 ish-orange (10 F^ 7/6), thick-bedded.

Mudstone: phosphatic, calcareous, 1. 4 crumbly, light-brownish-gray (10F.B 7/1); apatite is finely pelletal. Fossil- colln. No. 11657.

Mudstone: crumbly, light-brown . 4 100. 3 (7.5F^ 5/4), fissile.

Phosphorite: silty, crumbly, very pale . 2 100. 5 brown (10F^ 7/2), nodular and finely pelletal.

Mudstone: plastic, moderate-reddish- . 1 100. 6 brown; grades from bed below.

Phosphorite and mudstone, inter- 1. 7 102. 3 bedded: crumbly yellowish-gray (10 F^ 7/1) thick-bedded finely pel letal muddy phosphorite interbedded with crumbly grayish-brown (7.5 YR 3/2) finely pelletal phosphatic mudstone; grades from bed below.

Mudstone: plastic, moderate-yellow- .5 102. 8 ish-brown (10F.K 5/6), fissile; bed is sheared.

Mudstone: soft, grayish-brown (10F.B 4/2).

Phosphorite: soft, brownish-gray (10F.K 3/2), finely pelletal.

Mudstone: phospbatic, soft, moderate- brown (7.5YR 4/4); apatite if finely pelletal.

Phosphorite: soft, brownish-gray (10F^ 3/2), finely pelletal; grades from bed below.

Mudstone: soft, light-brown (7.5YR 5/4), thin-bedded; grades from bed below.

Mudstone: phosphatic, soft, grayish- brown (7.5F.K 3/2), fissile; apatite is finely pelletal.

Phosphorite: sandy, medium-hard, dark-gray (V 3), thick-bedded; most of apatite is apparently aphanitic; sand is fine; contains glauconite and phosphorite nodules as much as 15 mm in diameter. Fossil-colln. No. 11656.

Franson Tongue of Park City Formation:Limestone: medium-hard, light-brown

ish-gray (10F^ 6/1), thick-bedded, granular.

Limestone: hard, very pale orange (7.5F.R 8/2), very thick bedded; con tains up to 20 percent of recognizable bryozoan fragments. Fossil-colln. No. 11653.

Limestone: hard, very pale orange 9. 0 123. 7 (7.5F^ 8/2), very thick bedded, skeletal; contains a few interbeds of chert.

Limestone: hard, light-brownish-gray 4. 6 128. 3 (10 F^ 5/1), very thick bedded, skeletal. Fossil-colln. No. 11652.

Limestone: cherty, silty, hard, light- 31. 0 159. 3 brown (7.5F^ 6/4), thick-bedded, aphanitic.

Siltstone: carbonatic, hard, pale-brown 25. 0 184. 3 (10F^ 6/2), thick-bedded. Fossil- colln. No. 11651.

Sample

345

Uranium

Acid Radiometric Chemical insoluble eTT U

ERG-350 14. 3 26. 9 0. 002

349 2.

348 10.

5 20. 3 . 001

6 45. 1 . 007

. 2

. 2

. 1

. 4

. 5

. 6

1. 1

103. 0 '

103. 2

103. 3

103.7

104. 2

344 23.

343 6.

104. 8 342 8.

105. 9 341 16.

1. 8 107. 7 340

7.0 114.7 ___.___.__

347 8. 6 54. 9 . 004

346 17. 0 37. 1 006

1. 5 72. 9 . 003

7 23. 7 007

7 63. 2 003

5 56. 3 . 005

9 25. 4 . 009

5. 0 .001

709-931 O 63- -14


Little Sheep Creek, Mont., lots 1294 and 1295 Continued


Bed Description


F-73_ _________ Limestone and chert, interbedded:very pale orange (7.5 YR 8/2) thick- bedded skeletal limestone interbedded with very pale orange (10 YR 8/2) thick-bedded chert. Fossil- colln. No. 11650.

74__________ Limestone: hard, light-brownish-gray(IOYR 5/1), very thick bedded, finely skeletal; contains approxi mately 30 percent recognizable brachiopod valves and fragments. Fossil-colln. No. 11649.

72__________ Limestone: medium-hard, yellowish- gray (2.5 YR 8/2), thick-bedded, skeletal.

?!__________ Dolomite: hard, yellowish-white (2.5F9/2), very thick bedded, skeletal.

70__________ Dolomite: medium-hard, yellowish- white (2.5 Y 9/2), very thick bedded, skeletal.

69_ _________ Dolomite: hard, pale-brown (2.5 Y 6/2),thick-bedded, aphanitic.

68__________ Dolomite: hard, yellowish-gray (2.5 Y8/2), very thick bedded, aphanitic.

67__________ Sandstone: medium-hard, pale-brown(IOYR 5/2), thick-bedded, fine grained. Fossil-colln. No. 11648.


(66).-____--_ Covered.._________________________R-65__ ________ Chert: medium-hard, pale-orange

(7.5 YR 8/4), thin-bedded. 64__________ Phosphorite: muddy, medium-hard,

light-gray (N 7), thick-bedded, finely pelletal. Fossil-colln. No. 11647.

63__________ Phosphorite: sandy, medium-hard,light-gray (N 7) to brownish-gray (IOYR 4/1), thin-bedded, nodular, skeletal, finely pelletal; nodules are as much as 5 mm in diameter; con tains glauconite; irregular contact with bed below.

62__________ Chert: hard grayish-brown (7.5F.B4/2) thick-bedded chert interbedded with hard light-yellowish-brown (IOYR 6/4), thick-bedded chert.

61__________ Mudstone: cherty, medium-hard,brownish-gray (10F.R 4/1), thick- bedded.

60__________ Chert: hard dusky-brown (IOYR 2/2)thin-bedded chert interbedded with hard light-brown (7.5YR 5/6) thin- bedded chert.


M-59_________ Phosphorite: muddy, crumbly, brown ish-black (IOYR 2/1), thin-bedded, very finely pelletal.

58_ ________ Mudstone: soft, pale-brown (IOYR6/2) to moderate-yellowish-brown (IOYR 4/4), thin-bedded.

57_________ Mudstone: soft, moderate-yellowish- brown (IOYR 5/6), thin bedded.

56_ ________ Mudstone: phosphatic, crumbly,dusky-brown (IOYR 2/2), thin-bed ded, very finely pelletal.

55_ ________ Mudstone: soft, dark-yellowish-orange(IOYR 6/8), thin-bedded.

54_ ________ Mudstone: phosphatic, soft, dusky- brown (IOYR 2/2), thin-bedded.

53_________ Mudstone: soft, dark-yellowish-orange(IOYR 6/8), thin-bedded.


(feet) (feet)

11. 0 195. 3

6. 0 201. 3

4. 7 206. 0

7. 0 213. 0

4. 0 217. 0

12. 0 229. 0

12. 0 241. 0

4. 5 245. 5

30. 0 6. 0

275. 5281. 5

1. 1 282.

282. 8

13. 3 296. 1

9. 3 305. 4

8 306. 2

8 307. 0

307. 7}

1. 8 309. 5

. 3 309. 8\

1.4 311.2

. 5 311. 71

.2 311.91

Uranium

SampleAcid


eU U

CWT-339

338

337

336

335

334

333

332

331

0.6

25.3

88. 7 0. 001

2.9

16. 5

8. 3

9. 2

17. 8

92. 5

87.2

83. 8

39. 5

79. 7

62. 3

51. 8

008

001

002

002

Oil

003

006

007

0. 008

Oil

006

006


Little Sheep Creek, Mont., lots 1294 and 1295 ContinuedChemical analyses (percent)

Uranium

Bed Description

Meade Peak Phosphatic Shale Member ofPhosphoria Formation Continued

M-52- ________ Mudstone: phosphatic, soft, dusky- brown (10 YR 2/2), thin-bedded.

51_________ Phosphorite: crumbly, dusky-brown(10 YR 2/2), thin-bedded, medium- pelletal. Fossil-colln. No. 11646.

50_________ Mudstone: soft, moderate-yellowish- brown (10 YR 5/6), thin-bedded.

49_________ Phosphorite: siltv, soft, dusky-brown(IQYR 2/2), thin-bedded, finely pelletal. Fossil-colln. No. 11645.

48--__-_.__ Phosphorite: crumbly, brownish-gray (IQYR 3/1), thick-bedded, skeletal, and coarsely pelletal and oolitic.

47_________ Phosphorite and mudstone, interbed-ded: soft medium-gray (N 5) thin- bedded nodular and finely pelletal phosphorite interbedded with soft grayish-brown (7.5YR 3/2) to weak- yellowish-orange (IQYR 7/6) thin- bedded phosphatic mudstone; nod ules are as much as 3 mm in diameter.

46 _________ Phosphorite: crumbly, medi um-gray(N 5), thick-bedded, coarsely pel letal.

45_-------- Phosphorite: medium-hard, medium- gray (N 5), thick-bedded, skeletal, finely pelletal and oolitic.

Grandeur Tongue of Park City Formation;basal part not exposed:

G-44__________ Sandstone: medium-hard, very palebrown (IQYR 7/2), thin-bedded, very fine grained; contains phos phatic skeletal fragments; grades from bed below.

43__________ Sandstone: dolomitic, hard, yellowish,gray (10 YR 8/1), very fine grained; beds G-42 and G-43 are separated by a block of dolomite 3 ft thick that is bounded by faults and is probably equivalent to part of bed G-42. Scattered phosphatic skeletal frag ments in the upper part of bed G-42 indicate that little or no thickness is missing.

42__________ Dolomite: hard, pale-brown (2.5Y 6/2),very thick bedded, aphanitic.

41__________ Mudstone: dolomitic, crumbly, yellow ish- gray (2.5 YR 7/2), thin-bedded.

40___-______ Carbonate rock: hard, light-brownish- gray (IQYR 6/1), thick-bedded, aph anitic.

39_--------- Mudstone: medium-hard, light-pink ish-gray, thin-bedded.

38______-___ Mudstone: dolomitic, medium-hard,yellowish-gray (IQYR 7/1), thick- bedded.

37_----_____ Mudstone: dolomitic, medium-hard, dusky-pink, thick-bedded.

36_ _________ Mudstone: dolomitic, medium-hard,weak-yellowish-orange (2.5Y 7/4), thin-bedded.

35____-____- Mudstone: dolomitic, medium-hard, moderate-reddish-brown (10 YR 5/4), thin-bedded.

34__________ Similar to bed G-35- _______________33____ ______ Mudstone: dolomitic, medium-hard,

moderate-reddish-brown (IQYR 5/4), thin-bedded.

32__________ Similar to bed G-33_ ______-__-___-_31-.___-_-__ Mudstone: dolomitic, soft, weak-yel

lowish-orange (2.5 Y 7/4), thin-bed ded.


(feet) (feet)

0. 6 312. 5

1. 3 313. 8

1. 4 315. 2

1. 5 316. 7

1. 2 317. 9

. 8 318. 7

Sample

CWT-330

329

328

327

ERG-326

325

Acid Radiometric Chemical P.Os insoluble «U U

9. 4 44. 8 0. 008

26. 5 16. 0 . 018

6. 4 65. 3 . 006

20. 3 24 3 . 007

33. 0 1. 7 . 008

21. 2 28. 5 . 008

0. 006

. 017

. 004

. 006

. Oil

. 008

. 3 319. 0

1. 2 320. 2

. 2 320. 4

6. 0 326. 4

324 32. 4 5. 0 . 008 .008

10. 6

Q o

4. 7

. 1

. 9

. 3

ft 9

4. 8

1 1 91 Q 4.

10.0. 2

QQ.7 f)

340.0

0.4.4. 7

344. 81

345. 7

346.0

QCO 9

o r 17 f\

QftO O

001 /?

391. 6391. 8

CWT-323 pp-pf* 099

391

090

CWT 319

01 O

QI 7T?~D f~* Q1 K

QI C

. 3

9

. 1

. 1

9

. 1

.0

.0

. 1

1cc

3

9c

PL7

63.

70.79

64.

5

7

7

1

1

7Q

0

.001 _______

.002 _______

.0005 -------

.002 __--__.

.002 _______

.002 _______

.004 _______

.001 ___----

.002 _____--






Grandeur Tongue of Park City Formation;basal part not exposed Continued

G-30-_________ Dolomite: medium-hard, yellowish- 1.3 393. 1white (WYR 9/1), thick-bedded, aphanitic.

29__________ Mudstone: calcareous, medium-hard, 1. 2 394. 3weak-yellowish-orange (2.5F 8/4), thick-bedded.

28_-_--_____ Mudstone: calcareous, hard, light-gray .7 395.0 (N 8), thick-bedded; contains a few irregular nodules of chert; irregular contact with bed below.

27_---______ Dolomite: hard, very pale orange 6.3 401.3(WYR 8/2), thick-bedded, aphanitic; contains many chert nodules averag ing 0.3 ft in diameter.

26 ------- Dolomite: hard, yellovish-gray (2.5 Y 2.1 403.48/2), very thick bedded, aphanitic.

25__________ Dolomite: muddy, medium-hard, weak .8 404.2yellowish-orange (2.5F 8/4), thin- bedded, aphanitic.

24__-_______ Dolomite: muddy, very pale orange 1. 6 405. 8(WYR 8/2), thick-bedded.

23__-------- Dolomite: hard, very pale orange 3.5 409.3(WYR 8/2), thick-bedded, aphanitic. Fossil-colln. No. 11644.

22._________ Dolomite: medium-hard, yellowish- 7.1 416.4gray (2.5 Y 8/2), thick-bedded, apha nitic; contains chert nodules averag ing about 0.1 ft in diameter.

21__________ Limestone: dolomitic, medium-hard, yel- 5.6 422.0lowish-gray (WYR 8/1), thin-bedded; in fault contact with unit below.

20__________ Limestone: medium-hard, yellowish- 3. 8 425. 8gray (WYR 8/1), thin-bedded, apha nitic; in fault contact with unit be low.

19___ ______ Dolomite: medium-hard, yellowish- 1. 8 427. 6gray (2.5 Y 7/2), thick-bedded, apha nitic; contains numerous chert nod ules averaging 0.2 ft in diameter.

18__________ Dolomite: medium-hard, very thick 14.4 442.0bedded, aphanitic; color ranges from pale-brown (2.5F 5/2) at base to light-gray (N 7) at top. Fossil- colln. No. 11643.

17__________ Limestone: hard, pale-brown (WYR 2.0 444.06/2), thick-bedded. Fossil-colln. No. 11642.

16_________ Limestone: cherty, hard, light-brown- 2. 1 446. 1ish-gray (WYR 6/1), very thick bedded.

15__________ Limestone: muddy, hard, grayish-brown 1.4 447.5(2.5F3/2), very thick bedded, apha nitic; in fault contact with unit below.

14__________ Dolomite: medium-hard, yellowish- 2.4 449.9gray (2.SYR 8/2), very thick bedded.

13_-----____ Dolomite: muddy, medium-hard, yel- 1.8 451.7 lowish-gray (2'.5YR 8/2), very thick bedded, aphanitic.

12__________ Mudstone: calcareous, soft, weak-yel- .2 451.9low ish-orange (2.5F 7/4), thin- bedded.

!!__________ Dolomite: calcareous, muddy, medium- 1.7 453.6hard, very pale orange (1QYR 9/2), thin-bedded, aphanitic.

10_-----___- Sandstone: calcareors, hard, yellowish- 7.4 461.0 white (WYR 9/1), thick-bedded, cross-bedded, fine-grained; in fault contact M ith unit below .

9__----_____ Sandstone: calcareous, hard, very pale 2.3 463.3 orange (WYR 8/2), thin-bedded, fine grained.

Uranium

Sample P.05Acid


eTJ U



Bed



Grandeur Tongue of Park City Formation; basal part not exposed Continued

Sandstone: soft, pale-yellovrish-orange 7. 5 470 8 (2.5 Y 9/4), thick-bedded, fine grained.

Sandstone: soft, pale-yellovrish-orange 7. 8 478. 6 (2.5 Y 9/4), thick-bedded, fine grained.

Limestone: sandy, hard, yellowish-gray 3. 0 481. 6 (IOYR 7/1), thin-bedded; sand is fine; irregular contact with bed below.

Dolomite: silty, hard, yellowish-gray 2. 5 484. 1 (10 YR 7/1), very thick bedded, aphanitic.

Siltstone: crumbly, light-yellowish- . 3 484.4 brown (2.5 Y6/4).

Dolomite: hard, light-brownish-gray . 5 484.9 (10 YR 6/1), thick-bedded, apha nitic.

Dolomite: silty, hard, pale-brown(2.5 Y . 2 485. 1 6/2), fissile, aphanitic.

Dolomite: hard, yellowish-gray 2. 1 487. 2 (10YR 7/1), thick-bedded, aphanitic; contains a few chert nodules as much as 0.1 ft in diameter; underlying beds are covered.


Uranium

Acid Radio-metric Chemical insoluble eU U

Crooked Creek, Mont., lots 1296 and 1297[Grandeur Tongue of Park City Formation and parts of Phosphoria Formation measured in two bulldozer trenches near the head of Crooked Creek SWH sec. 1, T. 15 S.,

R. 8 W., Beaverhead County, Mont., from southeastward-dipping strata near the south end of a large anticlinal structure. Beds Q-l through F-69 (lot 1296) measured at upper trench from beds striking N. 60° E. and dipping 65° SE; beds Rt-71 through To-107 (lot 1297) described at the lower trench (350 feet east of upper trench) from overturned beds striking N. 50° E. and dipping 70° NE. Retort Phosphatic Shale Member of the Phosphoria Formation is so strongly sheared that the thickness and stratigraphic sequence may be incorrect. Section measured by E. R. Cressman and W. H. Wilson and sampled by J. L. Elliott, B. K. Replogle, and W. J. Garmoe, in July 1949. Samples analyzed for P2 O5 and acid insoluble by U.S. Bur. of Mines and tor uranium by U.S. Geol. Survey]

To-107.

106.

Rt-105---

102_

101-

100.

99_-

98_.

97.-

Description

Tosi Chert Member of Phosphoria Forma tion, lower part:

Chert: muddy, hard, grayish-brown (10YR 4/2), thick-bedded; grades from bed below; overlying beds are covered.

Chert: argillaceous, hard, grayish- brown (IOYR 4/2), thick-bedded.


Mudstone: phosphatic, crumbly, dusky-brown (10 YR 3/2), thin-bed ded; apatite is very finely pelletal.

Mudstone: plastic, moderate-yellow ish-brown (10 YR 5/6).

Mudstone: dusky-brown (10 YR 3/2), fissile; contains a few irregular lami nae of very fine grained apatite pellets.

Mudstone: soft, duskv-brown (IOYR 3/2).

Mudstone: plastic, moderate-yellow ish-brown (10 YR 5/6).

Mudstone: phosphatic, soft, dusky- brown (10 YR 3/2); grades from bed below.

Mudstone: soft, moderate-yellowish- brown (10 YR 5/6).

Mudstone: soft, dusky-brown (IOYR 3/2); grades from bed below.

Mudstone: soft, mottled brownish- gray (IOYR 3/1) and pale-brown (IOYR 5/3); bedding is contorted and sheared.

Thickness (feet)

11.7

. 2

1.7

4. 1

.2

4.3

1.8

1.7

4.8


Cumulativethickness

(feet)

11.7

Uranium

Sample PsOsAcid

insolubleRadio-

metric e~UChemical

U

15. 2 26. 9 WHW-636 1.3

27.3

ERG-635

634

633

632

631

4.4

7.4

13.7

7. 5

6. 5

82.0

65. 5 0. 003

56. 1

45.8

53.9

48.0

004

004

004

004


Crooked Creek, Mont., lots 1296 and 1297 Continued

Thickness Bed Description (feet)


Rt-96 ________ Similar to bed Rt-97---------_---_- 3.895____---_- Similar to bed Rt-97_-__------------ 4.394____-___- Similar to bed Rt-97--------------_ 4.093.___-____ Mudstone: soft, mottled brownish- 3. 3

gray (WYR 3/1) and pale-brown (10 YR 5/3), thick-bedded.

92__ _______ Mudstone: soft, mottled brownish- .9gray (WYR 3/1), and pale-brown (10 YR 5/3); bedding is contorted and sheared, and nearly every surface is slickensided.

91__-_-___- Mudstone: soft, mottled brownish- 4. 4 gray (IQYR 3/1) and pale-brown (WYR 5/3); bedding is contorted and sheared, and nearly every sur face is slickensided; contains several lenses averaging 0.2 ft thick and 1.0 ft long of yello\\ish-gray (WYR 7/1) mudstone.

90___----_- Similar to bed Rt-91_- _----------- 4.589-_-_---__ Phosphorite: muddy, medium-hard 3. 5

moderate yello\\ ish-brown (WYR 5/6).

88----____- Mudstone: soft, black (N 2), thin- 5.0 bedded; grades from bed below.

87____---__ Carbonate rock: muddy, phosphatic, 1.7 soft, black (N 1), thick-bedded, aphanitic; apatite is medium pelletal.

86 _________ Mudstone: medium-hard, ff ray ish-brown 3. 7(7.5 YR 4/2), thick-bedded; grades from bed below.

85_____---_ Phosphorite: muddy, medium-hard, . 3 brownish-gray (WYR 3/1), thin- bedded.

84.________ Phosphorite: muddy, soft, moderate- .5yellowish-brown (WYR 5/6), thin- bedded.

83_-------- Dolomite: muddy, soft, pale-brown 1.2(WYR 5/3), thick-bedded, aphanitic.

82_________ Phosphorite: muddy, soft, weak-yellow- 1. 3ish-orange (WYR 7/6), thick-bedded.

81_________ Mudstone: phosphatic, carbonatic, soft, 1. 2moderate-yellowish-brown (WYR 5/6).

80___-_---- Phosphorite: crumbly, brownish-gray . 2 (WYR 4/1), thick-bedded, medium- pell etal.

79____---_- Mudstone: soft, moderate-brown 1.0 (7.5 YR 4/4).

78_____-___ Phosphorite: medium-hard, light- .5 brownish-gray (WYR 5/1), thick- bedded, medium-pelletal.

77_________ Mudstone: soft, moderate-yellowish- . 2brown (WYR 5/6), thin-bedded

76_________ Phosphorite: medium-hard, brownish- . 1gray (WYR 3/1), thin-bedded, me dium-pelletal.

75_________ Mudstone: phosphatic, soft, moderate- . 6yellowish-brown (WYR 5/6), me dium-pelletal.

74. -------- Phosphorite: soft, light-brown (7.5 YR . 85/4^, finely pelletal.

73--_------ Phosphorite: medium-hard, light- .8brov nish-gray (WYR 6/1), thick- bedded, medium-pelletal.

72_____-_-_ Mudstone: soft, light-yellowish-brown 1. 6 (WYR 6/4).

Chemical analyses

Cumulativethickness

(feet)

62. 4

79.8

81. 5

85. 2

85. 5

86.0

90.9

91. 4

91. 6

91.7

92.3

Sample

49.9 ERG-63054. 2 629 58. 2 628 61. 5\

627

626

71.3 625 74. 8 WHW-624

623

622

621

384

38387. 2

88. 5

89. 7 ERG-382

381

95. 5

380

379

378

Uranium

Acid Radio- Chemical insoluble metric e\J II

7. 1 48. 3 0. 0046. 4 47. 3 . 0045. 5 48. 3 . 004

3. 6 53. 1 . 003

7. 5 36. 0 . 005 0. 0005

7. 6 37. 414. 5 32. 9

7. 4 40. 7

8. 6 18. 7

5. 2 59. 6

.005.004

.004

.004

.003

.005

18.3 31.3 .005 __---_-

8.1 48.0 .003 __-.--.

8.7 45.3 .004 ___--_.

18. 3 35. 3 . 006 . 005

13. 7 47. 0 . 006 .005

27. 9 14. 3 . 007 . 006

4.7 68.5 .004 _______




Bed Description

Franson Tongue of Park City Formation,basal beds:

F-71. ____-__- Sandstone: phosphatic, hard, light- brown (7.5YR 5/4), very fine grained; contains glauconite.

(70)_________ Unknown stratigraphic interval be tween beds F-69 and F-71.

69-_____-__- Sandstone: dolomitic(?), hard, light- gray (N 7), thick-bedded, very fine grained. Fossil-colln. No. 11694.

68___------- Dolomite: hard, light-gray (JV7), thin- bedded, aphanitic.


R-67___ _______ Chert: brittle, light-brownish-gray(1QYR 6/1), thin-bedded.

66__________ Dolomite: cherty, medium-hard, yel lowish-gray (1QYR 7/1), thin-bedded; contains a few stringers and laminae of chert averaging 1 mm thick.

65_--_---__- Dolomite: hard, pale-brown (10 YR 6/2), thick-bedded, aphanitic.

64__________ Mudstone: soft, pale-brown (7.5YR5/2), thin-bedded.

63________ Chert: brittle, brownish-gray (10 YR4/1), thick-bedded.

62__________ Mudstone: soft, pale-orange (7.5YR8/4), thin-bedded; contains a few lam inae of fine-grained apatite pellets.

61 __________ Phosphorite: soft, moderate-yellowish- brown (10 YR 4/4), thin-bedded, medium-pelletal.

60___ _______ Phosphorite: sandy, medium-hard,dark-gray (N 4), thin-bedded, medium-pclletal; contains phosphatic skeletal fragments and a few angular chert fragments that average 7 mm in diameter.

59-_------__ Mudstone: soft, grayish-brown (7.5YR4/2), fissile.

58__________ Chert: sandy, medium-hard, brownish- gray (10KR 3/1), thin-bedded; sand is very fine.

57__________ Chert: soft, moderate-yellowish-brown(10 YR 5/6), thick-bedded; bed is composed of a felted mass of siliceous sponge spicules.

56__________ Mudstone: soft, grayish-brown (2.5KB3/2), thin-bedded; irregular contact with bed below.

55__________ Chert: hard, pale-brown (10YR 5/2),thick-bedded.

54__________ Similar to bed R-55_ ________-_-_-_-53__________ Similar to bed R-55; grades from bed

below. Meade Peak Phosphatic Shale Member of

Phosphoria Formation: M-52__________ Phosphorite: cherty(?), medium-hard,

medium-gray (N 5), thick-bedded, medium-pellet al.

51_ _________ Phosphorite: crumbly, pale-brown(7.5 YR 6/2), thin-bedded; finely pelletal.

50__________ Mudstone: plastic, light-yellowish- brown (10 KB 6/4); grades from bed below.

(feet)

5.9

11.4

. 5

3. 6

q Q

1. 2

. 7

.6

4. 3

1.0

.05

.05

. 1

.8

. 2

5 A

o n

K K

. 4

. 2

thickness (feet)

101.4

112.8

113. 2

116.9

126.8

128.0

128. 7

129. 3

133. 6

134. 6

134. 65

134. 7

134. 8 '

135. 6

135. 8

141. 2 '

144. 9150.4

150. 8

151.0

Uranium

Acid Radio- Chemical Sample PsOs insoluble metric «TJ U

ERG-377 13. 6 35. 3 0. 009 0. 009

376 1.2 84.8 .003 _______

375 24.5 26.0 .002 _______

374 10. 9 58. 8 .007 . 005

373 .3 89.0 .001 _______

372 .3 89.8 .001 _______371 1.0 87.5 .002 _______

370 23.1 28.0 .001 _______

1. 9 152. 9 369 80. 8 .003 .002



Bed

M-49.

48-

47.

46.

45.

44_

43 _

42.

40.

39-

38.

37.

36.

35.

34.

33__.

32--

31__

30__

29.

28.


Description

Meade Peak Phosphatic Shale Member of Phosphoria Formation Continued

Dolomite: muddy, medium-hard, light- yellowish-brown (10 YR 6/4), very thick bedded, aphanitic.

Phosphorite: soft, pale-brown (10 YR 5/3), thin-bedded, finely pelletal.

Mudstone: dolomitic(?), soft, mod erate-yellowish-brown (10 YR 5/6), thin-bedded.

Phosphorite: soft, pale-brown (10 YR 5/3), thin-bedded, finely pelletal.

Mudstone: dolomitic(?), soft, mod erate-yellowish-brown (1QYR 5/6), thin-bedded.

Phosphorite: crumbly, light-brownish- gray (10 YR 5/1), finely pelletal.

Mudstone: dolomitic, soft, light-yel lowish-brown (10 YR 6/4), thick- bedded; grades from bed below.

Phosphorite: crumbly, yellowish-gray (10KB 7/1), medium-pelletal.

Mudstone: dolomitic, soft, light-yel lowish-brown (10 YR 6/4), thin- bedded.

Phosphorite: soft, pale-brown (1QYR 6/2), thin-bedded, finely pelletal.

Mudstone: carbonatic, soft, weak-yellow ish-orange (10 YR 7/6), thick-bedded.

Mudstone: plastic, grayish-brown (7.5 YR 3/2), thin-bedded.

Phosphorite: soft, yellowish-gray (IQYR 7/1), thin-bedded, medium- pelletal.

Mudstone: dolomitic, soft, light-brown (7.5YR 5/6), thin-bedded.

Mudstone: carbonatic, medium-hard, pale-brown (IQYR 6/2), very thick bedded.

Mudstone: carbonatic, soft, moderate- yellowish-brown (10 YR 5/6), thick- bedded.

Mudstone: plastic, grayish-brown (7.5 YR 3/2), thin-bedded.

Phosphorite: medium-hard, brownish- gray (10 YR 3/1), thin-bedded, finely pelletal.

Mudstone: soft, light-brown (7.5YR 5/6).

Phosphorite: medium-hard, brownish- gray (10 YR 3/1), thin-bedded, finely pelletal. Fossil-colln. No. 11693.

Mudstone: soft, light-brown (7.5F.R 5/6).

Phosphorite: medium-hard, light- brownish-gray (IQYR 5/1), thin- bedded, finely pelletal; contains phosphatic skeletal fragments and very fine quartz sand. Fossil-colln. No. 11692.

Uranium

Sample

ERG-368

P205

0.0

Acid Radiometric Chemicalinsoluble

36. 5 0. 001

U

. 1. 4

. 1

. 3

. 2

0 Q£t. O

. 2

. 9

. 2

. 6

. 2

. 1

1. 1

. 4

. 2

. 8

. 1

. 5

. 1

. 5

154.3

154. 7

154. 8

155. 1

155. 3

157. 6

157. 8 '

158. 7

158.9

159. 5

159. 7

1 fifl 91DU. £t

160. 3 >

161. 4

161. 8 '

162.0

162. 8 '

162. 9

163.4

163.5

164.0

367 5. 9 59. 7 . 005 0. 004

366 2.1 64.5 .002 _______

365 5.8 49.7 .004 _______

364 7.9 46.5 .004 _______

363 27.1 11.6 .020 _______

362 6. 4 38. 0 . 005 . 004

361 3.9 58.0 .004 _______

360 31.2 6.2 .016 .016

359 27. 3 17. 2 . 007 . 007




Bed

G-27-_.___

26_______

25_______

24______.

23__-_-._

22_______

21______

20_ __ _

19.

18------

17______

16__ __

15______

14_. ___

13__.__.

12.__.__

11____

10_____.

9

8-.___._

7

6-_-___ _

(5).._-__4______.

3__ _

(2)

Q-l.._ .

1 Description

Grandeur Tongue of Park City Formation:

pale orange (7.5 YR 8/2), thick- bedded, very fine grained.

aphanitic.

ffiay (IOYR 6/1), thick-bedded, aphanitic.

8/2), very thick bedded, aphanitic.

brown (IOYR 7/2), thick-bedded, aphanitic.

gray (IOYR 6/1), thick-bedded.

thick-bedded. Fossil-colln. No. 11691.

(10 YR 8/2), very thick bedded, aph anitic.

7/2), thick-bedded, aphanitic.

(2.5 F 5/4), thin-bedded.

7/1), very thick bedded, aphanitic.

lowish-orange (2.5F 7/4), thin- bedded.

7/1), thick-bedded, aphanitic. Fos sil-colln. No. 11690.

orange (IOYR 8/2), thin-bedded.

orange (10 F^ 8/2), thin-bedded.

pale brown (IOYR 7/2), thick- bedded, very fine grained.

pale orange (10 YR 8/2), very thick bedded, fine-grained.

bedded, aphanitic.


gray (2.5 F 8/2), very thick bedded, very fine grained.

gray (2.5 YR 8/2), thick-bedded, very fine grained.

lowish-gray (2.5F 8/2), very thick bedded, very fine grained.


gray (2.5F 8/2), very thick bedded, very fine grained.

Quadrant Formation: Sandstone: not measured. _ _

C"hickness i

(feet)

3.3

. 5

. 6

2.0

1. 3

8.9

10. 0

6.3

1. 6

. 9

3. 3

4. 5

5.0

5.8

6. 3

8. 0

10. 6

7. 2

7. 4

14. 1

7. 5

6. 0

10. 0 12. 5

13. 2

10. 0

Uranium

thickness Acid Radiometric Chemical (feet) Sample PtOs insoluble e\J U

167.3 __________ _---__ ______ ______ -._-_--

167.8 ___---_--. ______ ______ ______ _--_--_

168.4 __________ ______ ______ .__ __ _______

170.4 __________ --_-_. ______ ______ __-_--_

m 7

180.6 __________ ______ ______ ______ _______

190.6 __________ ______ ______ ______ __.--_-

IQfi Q

198.5 __________ ______ ______ ______ _______

1QQ 4

202.7 __________ ______ ______ ______ _______

207.2 __________ ______ ______ ______ _______

212.2 __________ ______ ______ ______ _______

218.0 ___-___--_ _---__ ______ ______ __.-_--

224.3 __________ ______ ______ ______ _______

232.3 __.__-___- ______ ______ ______ -___---

242. 9 _

250.1 __________ ------ ------ ------ -------

oc7 c

271.6 -_--_-_--_ ______ ______ ______ _______

279 1

285.1 ____------ __---- ______ ------ -------

295.1 ---------- ------ __---- ------ -------307.6 -_-__-__-_ -_--_- --.__- ______ _______

320.8 _--_------ ------ ------ ------ -------

330.8 --__ _ _-_ ------ ------ ------ -------


Hogback Mountain, Mont., lot 1299

[Permian rocks measured on Hogback Mountain, S^NW^ sec. 8, T. 11 S., R. 4 W., Madison County, Mont., on overturned west, limb of Ruby Valley syncline. Retort and Meade Peak Phosphatic Shale Members of Phosphoria Formation measured and sampled in hand trenches on east scarp of mountain; rest of section measured from natural exposure. Beds strike N. 40° E. and dip 50° W. Measured by W. II. Wilson, R. S. Jones, W. J. Garmoe, and B. K. Replogle and sampled by Replogle, J. L. Elliott, and R. F. Gosman, in August 1949. Petrographic descriptions by use of binocular microscope by E. R. Cressman. Analyzed for PzOs and acid insoluble by U.S. Bur. of Mines and for other constituents by U.S. Geol. Survey]


Bed

To-190_

Us-189-

To-188-

187_

186-

185-

184_

Us-183-

182-

To-180-

Us-179_

178_

177_

176_

175_

Description

Tosi Chert Tongue of Phosphoria Forma tion; includes two thin tongues of Shed- horn Sandstone:

Siltstone: carbonatic, sandy, medium- hard, pale-brown (2.5F 5/2), thin- bedded; contains glauconite. Fossil- collection number 11680. Overlying beds covered; top of bed To-190 may be Dinwoody contact.

Sandstone; cherty, carbonatic, medium hard, light-yellowish-brown (2.5F 6/4), thin-bedded, very fine grained; contains glauconite.

Chert: sandy, medium-hard, brownish- gray (10 YR 4/1), thin-bedded; con tains glauconite; sand is very fine.

Mudstone: medium-hard, pale-brown (2.5F 5/2), thin-bedded; contains glauconite.

Chert: carbonatic, hard, brownish-gray (10 YR 3/1), thin-bedded to fissile; contains glauconite.

Chert: calcareous, medium-hard, light- brownish-gray (10 YR 5/1), fissile; contains glauconite.

Chert: carbonatic, hard, grayish-brown (10 YR 4/2), thin-bedded; contains glacuconite.

Sandstone: hard, pale-brown (7.5YR 6/2), thick>bedded, medium-grained; contains glauconite.

Sandstone: cherty, carbonatic, hard, grayish-brown (10 YR 4/2), thin- bedded, fine-grained; contains glau conite.

Sandstone: hard, light-olive-gray (5F 5/2), thin-bedded, fine-grained; con tains glauconite and phosphatic skeletal fragments.

Chert: carbonatic, brittle, grayish- brown (10 YR 4/2), thin-bedded; con tains glauconite.

Upper tongue of Shedhorn Sandstone; con tains several beds of Tosi Chert Member of Phosphoria Formation.

Sandstone: hard, light-olive-brown (2.5F 5/4), very thick bedded, very fine grained; contains glauconite; grades from bed below.

Sandstone: medium-hard, light-yellow ish-brown (2.5F 6/4), very thick bedded, fine-grained; contains glau conite; contains columnar bodies of sandstone(?) 10 mm in diameter and 1.0 ft long, some of which branch outward at base of column.

Sandstone: hard, pale-brown (2.5F 6/2), thick-bedded; irregular contact with bed below.

Dolomite: sandy, hard, pale-brown (10 YR 6/2), very thick bedded, fine grained; sand is very fine.

Sandstone: medium-hard, pale-brown (2.5F 5/2), very thick bedded, fine grained; contains lenses of fine grained yellowish-gray (2.5F 7/2) sandstone; irregular contact with bed below. Fossil-collection number 11679.

Thick- Cumulativeness thiclcness(feet) (feet)

7. 3

. 8

2.9

. 5

1. 0

1. 6

1. 5

. 5

1. 9

. 5

3. 4

7. 3

8. 1

11. 0

11. 5

12. 5

14. 1

15.6

16. 1

18. 0

18. 5

21. 9

5. 9 27.

15. 5 43. 3

1. 5 44. 8

3. 3 48. 1

7. 5 55. 6

Uranium

ftample P205 fAcid Organic Radiometric Chemical nsoluble matter eV T T


Hogback Mountain, Mont., lot 1299 Continued


Tied Description

Upper tongue of Shedhorn Sandstone; con tains several beds of Tosi Chert Member of Phosphoria Formation Continued

To-174.______ Chert: sandy, hard, pale-brown (2.5F5/2), thick-bedded.

173_----__ Chert: sandy, ^ hard, yellowish-gray (IOYR 7/1), thick-bedded.

172-_____- Chert: sandy, hard, light-brownish- gray (IOYR 6/1), thick-bedded; irregular contact with bed below.

Us-171____-__ Sandstone: hard, pale-brown (IOYR 5/3), very thick bedded, fine-grained; grades from bed below.

170_------ Sandstone: hard, weak-yellowish- orange (2.51" 7/4), very thick bedded, fine-grained; contains a few chert- nodules 0.3 ft in diameter.

160_______ Sandstone: hard, weak-yellowish- orange (2.5}" 7/4), very thick bedded, fine-grained; contains a few chert nodules elongated parallel to bedding.

168_______ Chert: sandy, hard, thick-bedded; sandis very fine.

167___-___ Sandstone: hard, very pale brown (IOYR 7/2), fine-grained; contains a few chert nodules 0.2 ft in diameter.

166__---_- Sandstone: hard, light-yellowish- brown (IQYR 6/2), thick-bedded, fine-grained; irregular contact with bed below.

165_------ Sandstone: cherty, hard, light-gray(N 7), thick-bedded, fine-grained; irregular contact with bed below.

164__--_-_ Sandstone: cherty, hard, pale-brown (IOYR <ol2), thick-bedded, very fine grained; contains irregular bodies of sandy chert; irregular contact with bed below.

163 _______ Chert: sandy, hard, brownish-gray(IOYR 4/1), thin-bedded; contains a few columnar bodies of chert 0.25 ft diameter and 0.3 ft long; irregular contact with bed below.

162__-____ Sandstone: hard, pale-brown (IOYR 6/2), thick-bedded, very fine grained; contains glauconite; irregular con- contact with bed below. Fossil- collection number 11678.

Retort Phosphatic Shale Tongue of thePhosphoria Formation:

Rt-161_____-_ Phosphorite: muddy, soft, grayish- brown (7.SYR 4/2), fissile, finely pelletal.

160_----_- Phosphorite: medium-hard, grayish- brown (IOYR 4/2), thin-bedded, finely pelletal.

159______- Phosphorite: hard, light-brownish- gray (IOYR 6/1), thin-bedded, finely pelletal.

158-______ Mudstone: soft, very pale brown(IOYR 7/3), thin-bedded.

157_------ Mudstone: Phosphatic, medium-harddark-gray (N 3;, thin-bedded; apa tite is medium-oolitic and pelletal.

156_----__ Mudstone: phosphatic, soft, pale- brown (IOYR 5/3), thick-bedded; apatite is medium-pelletal.

155__-____ Dolomite: hard, light-brownish-gray (IOYR 6/1), thick-bedded, aphanitic.

154_______ Mudstone: phosphatic, medium-hard,dusky-browu (IOYR 2/2), thin-bedded apatite is finely pelletal.

Thick ness

1. 3

3. 6

3. 6

11. 9

10. 7

Cumulativethickness

(feet}

Uranium

56. 9

60. 5

64. 1

76. 0

86. 7

13. 3 100. 0

2. 1 102. 1

3. 8 105. 9

2. 8 108. 7

4. 4 113. 1

4. 8 117. 9

118. 7

3. 6 122. 3

1. 0 123. 3

1. 0 124. 3

. 7 125. 5

4. 7 130. 2

8 131.

3.0 134.0

. 7 134. 7

SampleAcid Organic Radiometric Chemical

insoluble matter eV U

RSJ-3553 26.7 22.9 ____ 0.009 0.006

3552 31. 2 14. 7 1. 2 . 007 . 010

WJG-3551 13.6 42.0 ____ .004 .005

3550 13.7 42.5 __._ .006 .006

3549 6. 95 41. 9 2. 00 . 003 . 003

3548 8.9 52.3 _._. .004 .002

488 GEOLOGY OF PERMIAN ROCKS

Hogback Mountain,

Bed Description

Retort Phosphatic Shale Tongue of thePhosphoria Formation Continued

Rt-153_______ Mudstone: medium-hard, grayish- brown (10 YR 4/2), thin-bedded.

152_______ Mudstone: phosphatic, hard, dark- gray (N 3), thick-bedded; apatite is finely pelletal.

151---____ Mudstone: medium-hard, brownish- black (10 YR 2/1), fissile.

150__-_--_ Phosphorite: hard, dark-gray (N 4), thin-bedded, finely pelletal.

149--___-- Mudstone: hard, brownish-gray (10 YR 3/1), thin-bedded.

148--_-___ Chert: carbonatic, hard, medium-gray (N 6), thick-bedded; contains some very fine quartz sand.

147________ Mudstone: phosphatic, medium-hard,brownish-black (IOYR 2/1), thin- bedded; apatite is medium-pelletal; grades from bed below.

146 _______ Mudstone: phosphatic, hard, dark- gray (N 4), thin-bedded; apatite is finely pelletal.

145_______ Sandstone: phosphatic, medium-hard,dark-gray (N 4), thin-bedded, very fine grained; apatite is finely pelletal; grades from bed below.

144_-_____ Phosphorite: muddy, sandy, medium- hard, light-brownish-gray (IOYR 5/1), thin-bedded, medium-pelletal; sand is fine.

143-_-_--- Chert: dolomitic, hard, medium-gray (N 5), very thick bedded; contains some very fine quartz sand; grades from bed below.

142 _______ Mudstone: phosphatic, hard, brownish- gray (IOYR 4/1), thin-bedded; apa tite is finely pelletal; contains some fine quartz sand.

141_______ Mudstone: phosphatic, hard, dark-gray(N 3), thin-bedded; apatite is me dium-pelletal.

140_______ Chert: carbonatic, hard, dark-gray(N 4), thick-bedded.

139_______ Mudstone: carbonatic, hard, black (TV 2),thin-bedded; irregular contact with bed below.

138 _______ Chert: sandy, hard, grayish-brown(7.5 YR 3/2), thick-bedded; sand is fine; irregular contact with bed below.

137_______ Mudstone: hard, dusky-brown (1077?2/2), thin-bedded; irregular contact with bed below.

136_______ Chert: hard, dark-gray (N 4), thick- bedded.

135__.____ Chert: hard, dark-gray (N 4), thin- bedded; contains some very fine quartz sand; irregular contact with bed below.

134____-__ Chert: argillaceous, hard, dark-gray (N 3), thin-bedded; irregular contact with bed below.

133-______ Chert: argillaceous, sandy, hard, light- brownish-gray (IOYR 5/1), thin- bedded; sand is very fine; grades from bed below.

132____--_ Chert: argillaceous, hard, very pale brown (10 YR 7/2), thin-bedded.

131__-____ Chert: sandy, muddy, hard, dark- yellowish-brown (IOYR 4/2), thin- bedded; sand is very fine.

IN THE WESTERN PHOSPHATE FIELD

Mont., lot 1299 Continued


UraniumThick- Cumulativeness thickness(feet} (feet} Sample

Acid Organic Radiometric Chemical insoluble matter eIT IT

0.9 135.6 WJG-3547 5.7 63.9 ____ 0.004

. 9 136. 5 3546 16. 8 43. 3 3. 81 . 006

1.4 140.3

1. 3 141. 6

2. 4 144. 0

. 8 144. 8

1. 5 146. 3

1. 6 147. 9

1. 1 149. 0

1. 0 150. (T)

. 7 150. 7

2. 0 152. 1

1. 1 153. 8

. 3 154. 1

. 5 154. 6

2. 6 157. 2

2. 3 159. 5

2. 3 161. 8

2. 6 164. 4

3545 8. 3 54. 7

3544 3. 7 62. 4

3542 8. 8 63. 1

3541 11. 6 57. 6

3539 1. 8 55. 5

3538 12. 7 57. 3

3536 4. 3 55. 3

3535 2. 7 87. 2

3534 6. 1 71. 7

3533 1. 7 88. 1

. 005

. 002

3543 11. 3 49. 8 6. 41 . 005

0.004

.005

.007

. 002

. 007

. 004 . 005

. 004 . 005

3540 14. 2 53. 0 1. 46 . 005 . 005

. 000 . 001

. 003 . 004

3537 8. 1 66. 7 3. 71 . 003 . 004

. 002 . 003

. 001 . 002

. 004 . 004

. 002 . 002

3532 1.1 92. 8 ____ .000 . 002

3531 1. 7 88. 9 1. 11 . 002 . 003

3530 2. 8 85. 7

3529 3. 4 81. 4

. 002 . 002

. 002 . 002

Bed

Rt-130.

129.

128.

127.

126.

125.

124.

123.

122.

121.

120_

119.

118.

117.

116.

115.

114.

113.

112.

111.

110.

109.

108.

107_

106..

105-



489


Description

theRetort Phosphatic Shale Tongue of Phosphoria Formation Continued

Mudstone: phosphatic, medium-hard, grayish-brown (10 YR 4/2), thin- bedded; apatite is medium-pelletal.

Mudstone: phosphatic, medium-hard, dusky-brown (10 YR 2/2), thin- bedded; apatite is finely pelletal.

Dolomite: silty, hard, light-brown (7.5YR 5/4), thin-bedded, aphanitic.

Mudstone: phosphatic, plastic, dark- grayish-brown (IOYR 3/2), thin- bedded; apatite is medium-pelletal; grades from bed below.

Mudstone: phosphatic, hard, dark-gray (N 3), thin-bedded; apatite is me dium pelletal; grades from bed below.

Mudstone: phosphatic, medium-hard, brownish-gray (IOYR 4/1), thin- bedded; apatite is medium pelletal.

Mudstone: medium-hard, black (N 2), thick-bedded.

Phosphorite: hard, dark-gray (N 4), thin-bedded, coarsely pelletal; grades from bed below.

Mudstone: medium-hard, light-brown (7.5 YR 5/4), thin-bedded.

Phosphorite: muddy, hard, dark-gray (./V3), medium-pelletal.

Mudstone: medium-hard, brownish- gray (IOYR 3/1), thin-bedded.

Phosphorite: muddy, hard, dark-gray (./V4), thin-bedded, medium-pelletal.

Mudstone: medium-hard, brownish- black (IOYR 2/1), thin-bedded; grades from bed below.

Mudstone: hard, grayish-brown (2.5FR 3/2), thin-bedded.

Mudstone: plastic, moderate-orange (7.5 YR 6/8), thick-bedded.

Mudstone: hard, brownish-gray (10F.R 3/1), thin-bedded.

Phosphorite: muddy, medium-hard, pale-brown (10 YR 5/2), thin-bedded, finely pelletal.

Phosphorite: hard, light-brownish-gray (10 FR 6/1), thin-bedded, medium- pelletal and oolitic; grades from bed below.

Mudstone: crumbly, weak-yellowish- orange (10 YR 7/6), thick-bedded.

Mudstone: phosphatic, soft, grayish- brown (10 YR 4/2), thin-bedded; apatite is finely pelletal.

Mudstone: phosphatic, medium-hard, pale-brown (IOYR 5/3), thin-bedded; apatite is finely pelletal.

Mudstone: phosphatic, plastic, gray ish-brown (7.5 YR 3/2), thin-bedded; apatite is finely pelletal.

Phosphorite: hard, medium-gray (-/V6) thin-bedded, medium-pelletal; grades from bed below.

Phosphorite: muddy, hard, pale-brown (IOYR 5/2), thin-bedded, finely pelletal.

Phosphorite: muddy, hard, black (N 2),thin-bedded, finely pelletal.

Mudstone: medium-hard, light-gray (N 7), fissile.

Thick- Cumulative ness thickness (feet) (feet)

0. 5

. 5

1. 7

3. 0

. 8

. 7

.3

. 3

. 8

. 4

.8

. 4

2. 5

. 3

. 5

1. 0

1. 5

. 9

. 4

2. 6

1. 3

.7

1. 0

1. 7

1. 0

. 9

164. 9^1

165. 4r

167. 1

170. 1

170. 9

171. fr

171. 9

172. 2

173. 0]

173. 4

174. 2 :

174. 6

177. 1

177. 4'

177. 9

178. 9'

180. 4 >

181. 3

181. ?1

184. 3 1

185. 6 N

186. 3

187. 3

189. 0

190. 0

190. 9

Uranium


insoluble matter e~U U

WJG-3528 11. 2 54. 1 3. 80 0. 005

3527 5. 7 35. 4

3526 15. 6 43. 7

. 003

.007

0.007

.003

. 008

3525 12. 0 44. 4 10. 40 . 006 . 006

3524 12. 3 37. 5

3523 11. 0 47. 1

. 006 . 006

. 006 . 007

3522 11. 9 43. 4 10. 50 . 005 . 007

3521 6.3 51.3 ____ .006 .006

3520 2. 3 71. 0 . 004 . 002

3519 13. 1 48. 7 1. 81 . 006 . 006

3518 34.5 4.5 ____ .011 .013

3517 8. 1 55. 7

3516 10. 7 37. 3

. 005 . 004

. 006 . 007

3515 29. 3 10. 7 1. 69 . 013 . 015

3514 17.3 32.7 ____ .008 .011

3513 13.9 33.3 8.89 .009 .011




Bed

Rt-104.

103_

102.

101.

100-

99_.

98..

95.

94.

92.

91.

90.

Ls-84_

83_

82.

81-

Description

Retort Phosphatic Shale Tongue of the Phosphoria Formation Continued

Mudstone: hard, grayish-brown 10 YR 3/2), thick-bedded.

Mudstone: plastic, brownish-black (lOFfl 2/1), thick-bedded.

Mudstone: soft, grayish-brown (7.5Ffl 3/2), thin-bedded.

Mudstone: dolomitic, soft, black (N 1), thin-bedded; grades from bed below.

Mudstone: phosphatic, medium- hard, dark-gray (N 3), thin-bedded; apatite is finely pelletal.

Mudstone: plastic, moderate-brown (7.5 YR 4/4), thin bedded.

Phosphorite: muddy, medium-hard, black (A7 2), thin-bedded, mediuin- pelletal; pellets are concentrated in laminae and lenses.

Phosphorite: soft, yellowish-gray (10F.R 7/1), thin-bedded, medium- pelletal; grades from bed below.

Phosphorite: muddy, medium-hard, weak-orange (7.SYR 7/6), thick- bedded, medium-pelletal.

Mudstone: medium-hard, weak-yellow ish-orange (IOYR 7/6), thick-bedded.

Phosphorite: crumbly, medium-gray (N 6), thin-bedded, medium-pelletal; grades from bed below.

Phosphorite: muddv, medium-hard, dusky-brown (IOYR 2/2), thick- bedded, finely pelletal.

Mudstone: medium-hard, pale-brown (lOFfl 5/3), thick-bedded.

Mudstone: earthy, light-brown (7.5- YR 5/6), thick bedded.

Mudstone: hard, moderate-yellowish- brown (IOYR 4/4), thick-bedded; grades from bei below.

Mudstone: phosphatic, medium-hard, black (N 1), thick-bedded; apatite is finely pelletal.

Mudstone: earthy, light-brown (7.SYR 5/6), thin-bedded.

Phosphorite: hard, black (A7 2), thick- bedded, coarsely pelletai; contains some very fine quartz sand; grades from bed below.

Siltstone: hard, dark-gray (A7 3), thick- bedded.

Chert: brittle, brownish-gray (WYR 3/1), thin-bedded; contains glauconite and phosphatic skeletal frag ments; grades from bed below.

Lower tongue of Shedhorn Sandstone:Sandstone: hard, very pale brown

(WYR 7/2), very thick bedded, fine grained; grades from bed below.

Sandstone: hard, very pale brown (IOYR 7/2), very thick bedded, fine grained; grades from bed below.

Sandstone: hard, light-brownish-gray (IOYR 6/1), very thick bedded, fine grained; contains chert lenses 0.3 ft in diameter in layers at base and 4.0 ft above base; contains phosphatic skeletal fragments.

Dolomite: hard, yellowish-gray (WYR 7/1), thick-bedded, aphanitic; grades from bed below.


Uranium

. 8 196. 9

. 7 197.

.9 198.51

. 8 199. 3

. 3 199.

. 2 199.

. 9 200.

.6 201.3

1. 2 202. 5'

. 1 202. 6

. 3 202. 9

. 7 203. 6

1. 5 205. 1

1. 3 206. 4

5.4 211.8

5. 0 216. 8

3. 7 220. 5

Acid Organic Radiometric Chemical .^Sample PzOs insoluble matter eU U

WJG-3512 5. 3 59. 0

3511 5.7 37.5

0. 004 0. 005

. 005 . 006

3510 9. 7 43. 3 7. 63 . 007 . 008

3509 16.6 30.7 __._ .009 .008

3508 32. 1 5. 2 . 008 . 010

3507 10. 1 57. 5 1. 23 . 003 . 003

3506 29.7 18.5 _.__ .008 .010

3505 12. 3 32. 7 . 003 . 004

3504 6. 0 64. 5 1. 35 . 004 . 003

3503 9. 8 46. 2 _ _ _ _ .006 . 006

3502 22. 8 23. 6 . 009 . 010

3501 3. 1 80. 5 1. 98 . 003 . 002




Bed Description

Lower tongue of Shedhorn Sandstone Con. Ls-80_------- Sandstone: hard, very pale brown

(1QYR 7/2), very thick bedded, fine grained; contains irregular chert nodules 0.5 ft in diameter near top; contains phosphatic skeletal frag ments.

Franson Member of Park City Formation; contains some thin tongues of Shedhorn Sandstone:

F-79.________ Dolomite: cherty, hard, yellowish-gray(WYR 7/1), very thick bedded, aphanitic.

Ls-78- _______ Sandstone: dolomitic, medium-hard,pale-orange (7.5 YR 8/4), thin- bedded, fine-grained.

F-77-________ Dolomite: hard, yellowish-gray (10 YR7/1), thick-bedded, aphanitic; sandy in lower 5 ft; irregular contact with bed below.

76_________ Dolomite and chert, interbedded: hardlight-brownish-gray (10 YR 6/1), thick-bedded aphanitic dolomite interbedded with thick-bedded chert; dolomite contains some chert nodules and is muddy in lower 15 ft.

75_-------- Dolomite: hard, yellowish-gray (10 YR7/1), very thick bedded, aphanitic. Fossil collection number 11677.

Ls-74 ________ Sandstone: hard, yellowish-gray (10 Y R7/1), thick-bedded, fine-grained; grades from bed below.

Rex Chert Tongue of Phosphoria Forma tion; contains thin tongue of Shedhorn Sandstone near top:

R-73- _______ Dolomite: sandy, cherty, hard, yellow ish-gray (10 YR 7/1), very thick bedded, aphanitic; sand is very fine; contains phosphatic skeletal frag ments and glauconite.

Ls-72_ _______ Sandstone: cherty, hard, yellowish- gray (10 YR 7/1), very fine grained.

R-71_________ Chert: brittle, yellowish-gray (WYR7/1), poorly bedded.

70_ ________ Chert: hard, light-brownish-gray(10 YR 5/1) thick-bedded.

69.________ Chert: hard, brownish-gray (-IQYR3/1), thin-bedded.

68. ________ Chert: brittle, light-brownish-gray(WYR 6/1), thick-bedded; grades from bed below.

67.. ________ Chert: brittle, dark-gray (N 3), thick- bedded.

Meade Peak Phosphatic Shale Tongue ofthe Phosphoria Formation:

M-66_ _______ Phosphorite: sandy, medium-hard,pale-brown (WYR 6/2), thin-bedded, finely pelletal; contains phosphatic skeletal fragments.

65. _______ Mudstone: medium-hard, light-yellow ish-brown (WYR 6/4), thin-bedded; grades from bed below.

64________ Siltstone: soft, moderate-yellowish- brown (10 YR 4/4), thin-bedded.

63 ________ Phosphorite: muddy, soft, dusky- brown (WYR 2/2), thin-bedded, very finely pelletal.

62 ________ Siltstone: soft, moderate-yellowish- brown (10 YR 4/4), thin-bedded.

61________ Phosphorite: crumbly, dusky-brown(10 YR 2/2), thin-bedded, coarsely pelletal and oolitic.

Thick ness

Cumulativethickness

(feet)

Uranium

Sample P205Acid Organic Radiometric Chemical

insoluble matter eV U

4. 1 224. 6

10. 1 234. 7

8. 5 243. 2

24. 0 267. 2

22. 5 289. 7

46. 0 335. 7

10. 0 345. 7

10. 0 355. 7

2. 0 357. 7

14. 5 372. 2

5. 4 377. 6

1. 6 379. 2

30. 2 409. 4

2. 8 412. 2 WHW-3374 0. 4 64. 0 0. 002

1. 0 413. 2

2. 0 415. 2

1. 1 416. 3

. 1 416. 4

. 9 417. 3

4. 0 421. 3

3373 6. 0 67. 7

3372 8. 8 66. 5

3371 28. 8 16. 0

. 003

. 005 0. 004

.013 .013




Bed Description

Meade Peak Phosphatic Shale Tongue ofthe Phosphoria Formation Continued

M-60 ________ Phosphorite: medium-hard, light- brownish-gray (IOYR 5/1), thick- bedded, coarsely oolitic and pelletal; contains phosphatic skeletal frag ments. Fossil-colln. No. 11676.

59_ _______ Siltstone: hard, pale-brown (10FE6/2),thin-bedded. Fossil-colln. No. 71676.

Grandeur Member of Park City Formation: G-58_ _---___ Dolomite: hard, pale-orange (7.5 YR

8/4), very thick bedded, aphanitic.57- ------ Dolomite: silty, hard, pale-orange

(7.5 YR 8/4), very thick bedded, aphanitic.

56_________ Sandstone: muddy, dolomitic, medium- hard, very pale brown (IOYR 7/3), thin-bedded, very fine grained.

55----_--__ Similar to bed G-56_____-_--______-54 _______ Similar to bed G-56______---______-53_________ Similar to bed G-56___-_-__-___--__52--------- Similar to bed G-56_____----____ 51_________ Similar to bed G 56; grades from bed

below.50_ ________ Mudstone: dolomitic, medium-hard,

yellowish-gray (2.5 Y 7/2), thin- bedded.

49__-______ Similar to bed G 50; grades from bedbelow

48_________ Sandstone: silty, medium-hard, verypale brown (WYR 7/3), thin-bedded, very fine grained.

47 ------- Similar to bed G-48______________46_-----___ Dolomite: hard, light-gray (N 7),

thick-bedded, aphanitic.45_ ________ Dolomite: hard, very pale brown (10 YR

7/2), thin-bedded, aphanitic; con tains scattered chert nodules.

44_________ Dolomite: hard, yellowish-gray (IOYR7/1), very thick bedded; aphanitic.

43_________ Dolomite: hard, yellowish-gray (IOYR8/a), thick-bedded, aphanitic. Fossil collection number 11675.

42_________ Sandstone: muddy, hard, yellowish- gray (IOYR 8/1), very thick bedded, very fine grained.

41 _________ Dolomite: hard, yellowish-gray (IOYR7/1), thick-bedded, aphanitic.

40_________ Dolomite: hard, very pale orange (10 YR8/2), thin-bedded, aphanitic. Fossil- collection number 11674.

39_________ Dolomite: medium-hard, very paleorange (IOYR 8/2), thin-bedded, aphanitic.

38_________ Dolomite: hard, yellowish-white (IOYR9/1), very thick bedded, aphanitic.

37_________ Similar to bed G-38______-_--____-_36---______ Dolomite: hard, yellowish-gray (IOYR

8/1), thick-bedded, aphanitic.35_________ Sandstone: brittle, weak-yellowish-

orange (IOYR 7/6), very thick bedded, fine-grained.

34_________ Dolomite: brittle, light-brownish-gray(IOYR 6/1), thick-bedded, aphanitic.

33_________ Similartobed G-34___ _____________32_________ Similartobed G-34__-_-__ _______31_________ Dolomite: sandy, brittle, light-gray

(N 8), thin-bedded, aphanitic.


Uranium

6. 2 6.0 5.45. 56. 0

10. 833. 4

7. 8 6.0

13. 015.0

2. 5

Acid Organic Radiometric Chemical PaOs insoluble matter eV IT

0. 7 422. 0 WHW-3370b 23. 4 34. 1 0. 006 0. 006

1. 1 423. 1

3. 5 426. 6

3. 4 430. 0

7. 5 437. 5

443.7449. 7455. 1460. 6466. 6

4. 8 471. 4

4. 9 476. 3

11. 2 487. 5

498. 3531. 7

26. 4 558. 1

3. 0 561. 1

27. 2 588. 3

7. 3 595. 6

15. 0 610. 6

10. 8 621. 4

2. 6 624. 0

15. 0 639. 0

646.8652.8

6. 5 659. 3

12. 8 672. 1

685. 1700. 1702.6

3370a 8 91. 8 000 . 001

3369

3368

3367

3366336533643363qoco

3361

3360

3QKQ

K

g

. ?,

9. 1

9

. i

. i. i

11.5 ____

28.0 ____

70.3 ____

cc 9

n o

n 9

67.8 -___63.7 --_-

64.6 ____

7n ^

71.0 ___-

.001 -------

.001 -------

.002 __-__--

.001 -------

.001 -------

. 002 _-- ---

.002 - _-_

.002 -------

.002 -------

.001

.001 -__ _ _



Red

G-30_

29__.

28_

27. 26.

25.

23_

22_

20..

19.

18.

17.

16.

15.

14.

13

12.

11-

10.

Description

Grandeur Member of Park City Forma tion Continued

Sandstone: silty, dolomitic, brittle, light-yellowish-brown (2.5 Y 6/4), thin-bedded, very fine grained.

Dolomite: brittle, light-yellowish- brown (2.5 Y 6/4), thin-bedded, aphanitic; contains scattered black chert lenses 0.05 by 1 ft; grades from bed below.

Dolomite: hard, yellowish-gray (IOYR 7/1), thick-bedded, aphanitic; con tains numerous chert nodules 0.1 ft to 0.5 ft in diameter.

Similar to bed G-28____--_--------_Carbonaterock: hard, dark-gray (N3),

thick-bedded, aphanitic.Carbonate rock: hard, light-brownish-

gray (10 YR 5/1), thin-bedded, apha nitic. Fossil-colln. No. 11673.

Similar to bed G-25______----__--_-Carbonate rock: hard, pale-brown

(2.5 Y 6/2), thin-bedded, aphanitic.Sandstone: hard, yellowish-gray (IOYR

7/1), thick-bedded, fine-grained.Dolomite: hard, pale-brown (IOYR

6/2), thin-bedded, aphanitic.Sandstone: muddy, dolomitic, brittle,

light-yellowish-brown (10 YR 6/4), very thick bedded, fine-grained.

Chert: calcareous, brittle, white (N 9), very thick bedded.

Dolomite: brittle, light-brownish-gray (IOYR 6/ ), very thick bedded, aphanitic.

Sandstone: silty, dolomitic, brittle, weak-yellowish-orange (2.5 F 7/4), very thick bedded, fine-grained.

Dolomite: brittle, light-brownish-gray (IOYR 6/1), thick-bedded, aphanitic; grades from bed below.

Dolomite: brittle, very pale brown (IOYR 7/3), thick-bedded, aphanitic.

Sandstone: silty, hard, pale-brown (IOYR 6/2), thick-bedded, fine grained.

Dolomite: brittle, yellowish-gray (10FT? 7/1), thick-bedded, aphanitic.

Sandstone: silty, dolomitic, crumbly, weak-yellowish-orange (2.5F 8/4), fissile, very fine grained.

Dolomite: brittle, light-gray (N 7), thick-bedded, aphanitic.

Sandstone: brittle, weak-yellowish- orange (2.5F 8/4), thin-bedded, fine grained.

Dolomite: hard, yellowish-gray (IOYR 7/1), thick-bedded, aphanitic.

Sandstone: dolomitic, hard, very pale orange (7.5YR 8/2), thin-bedded, very fine grained.

Dolomite: brittle, yellowish-gray (IOYR 7/1), very thick bedded, aphanitic.

Sandstone: brittle, moderate-yellowish- brown (10 FT? 4/4), thick-bedded, very fine grained.

Dolomite: brittle, very pale brown (10 YR 7/2), thin-bedded, aphanitic; grades from bed below.

Dolomite: brittle, light-gray (N 7), fissile, aphanitic; grades from bed below.

2. 4

9. 4

15.05. 7

8. 5 2.6

3. 5

2.0

3. 0

5. 2

4. 0

2. 6

6. 5

1. 0

705. 0

714.4

9. 0 723. 4

738.4744. 1

4. 8 748. 9

757.4760.0

763. 5

772. 3

774.3

777.3

782. 5

786. 5

789. 1

. 3

.3

.3

. 1

1. 6

. 4

. 6

.3

3.0

.3

789. 4

789. 7

790.0

790. 1

791. 7

792. 1

792. 7

793. 0

796.0

796. 3

802. 8

803.8


UraniumThick- Cumulativeness thickness(feet) (feet) Sample PsOs

Acid Organic Radiometric insoluble matter ell

ChemicalU

709-931 O 63- -15




Bed

Thick- Cumulative ness thickness (feet)

Uranium

(feet) Sample PzOsAcid Organic Rad,iometric

insoluble matter eUChemical

U

G-3_ 2. 7 806. 5

806. 8

Description

Grandeur Member of Park City Forma tion Continued

Dolomite: medium hard, yellowish white (2.5 Y 9/2), thick-bedded, aphanitic.

Dolomite: silty, medium-hard, weak- yellowish-orange (2.5F 8/4), thin- bedded; dolomite is aphanitic.

Quadrant Formation:Sandstone: hard, yellowish-white (2.57 ____ ______ ___________ ____ ____ ____ ______ _______

9/2, thick-bedded, fine-grained.

Warm Springs Creek, Mont., lot 1300

[ Pennian rocks measured near Warm Springs Creek, N WH sec. 22, T. 9 S., R. 3 W., Madison County, Mont., near crest of small anticline. Retort Phosphatic Shale Tongue of Phosphoria Formation measured and sampled in hand trench; rest of section measured from natural exposures. Beds strike N. 30° E. and dip 2° N.W. Measured by W. H. Wilson, B. K. Replogle, and J. L. Elliott and sampled by Elliott, Replogle, and R. F. Gosman, in August 1949. Analyzed for P2 O 5 and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Q-i.

Bed

(42).

Us-41_

40_

39.

38.

37-

36.

35_

34-

To-33.

32-

31.

30.

29.



Upper member of Shedhorn Sandstone:Covered; contact between Dinwoody 4. 5 4. 5

and Shedhorn formations locatedapproximately by change in float.

Sandstone: medium-hard, yellowish- 4. 4 8. 9gray (107728/1), thick-bedded; fine grained; contains glauconite; gradesfrom bed below.

Chert: hard, light-brownish-gray 1. 4 10. 3(WYR 6/1), thin-bedded; containsglauconite; grades from bed below.

Sandstone: hard, pale-brown (WYR 5. 0 15. 35/3), medium-light-gray (N 7) onunweathered interiors of some frag ments, thick-bedded, fine-grained;contains glauconite; grades frombed below.

Sandstone: medium-hard, light-brown- 3. 0 18. 3ish-gray (WYR 5/1), thick-bedded,cross-bedded; fine-grained: containsglauconite.

Sandstone: medium-hard, light-brown- 17. 3 35. 6ish-gray (WYR 5/1), thick-bedded;fine-grained; contains glauconite;grades from bed below.

Similar to bed US-37 but does not 20. 0 55. 6contain glauconite; irregular contactwith bed below.

Sandstone: cherty, brownish-gray . 5 56. 1(1077? 4/1), thick-bedded, very finegrained; contains columns of fine grained sandstone that are perpendic ular to bedding.

Sandstone: hard, light-brownish-gray 2. 3 58. 4(WYR 5/1), thick-bedded; very finegrained; grades from bed below.


Chert: brittle, pale-brown (1077? 6/2), 6. 8 65. 2thick-bedded; grades from bed below.

Chert: hard, light-brownish-gray 32. 1 97. 3(WYR 6/1), thick-bedded.

dark-gray (N 3), thick- 21. 5 118. 8

Uranium

Acid Radiometric Chemical insoluble eU U

Chert: hard, bedded.



dark-gray (N 3), thin- 5. 0 123. 8

dark-gray (N 3), thin- 1. 9 125. 7 WHW-3385 0. 5 92. 8 0. 001


Warm Springs Creek, Mont., lot 1300 ContinuedChemical analyses (percent)

Uranium

Bed

To-28_

27.

Rt-26_

25_

24_

23.

22_

21.

20-

Ls-16.

15

Ls-11

10

R-9


Chert: hard, dark-gray (N 3), thin- bedded; grades from bed below.

Chert: hard, dark-gray (N 3), thin- bedded; contains thin mudstone partings between chert beds.


Phosphorite: muddy, medium-hard, grayish-brown (WYR 3/2), fissile; pelletal.

Phosphorite: muddy, crumbly, dark- gray (N 4), thin-bedded; very finely pelletal.

Phosphorite: muddy, crumbly, lami nated grayish-brown (7.5YR 4/2) and dark-gray (A'" 4), thin-bedded; argillaceous material is concentrated in grayish-brown laminae.

Phosphorite: medium-hard, dark-gray (N 4), thin-bedded, finely pelletal.

Mudstone: phosphatic, crumbly, dusky- brown (10 YR 2/2), thin-bedded; grades from bed below.

Mudstone: soft, brownish-gray (1QYR 4/1), thin-bedded.

Phosphorite: crumbly, dark-gray (Af 4), thin-bedded; finely pelletal.

Chert and mudstone, interbedded: hard, dark-gray (N 3), thin-bedded, chert interbedded with medium-hard light-brown (7.5YR5/&) thin-bedded cherty mudstone.

Chert: hard, dark-gray (N 3), thin- bedded.

Chert: hard, dark-gray (N 3), thick- bedded; contains glauconite.

Lower member of Shedhorn Sandstone:Sandstone: hard, light-brownish-gray

(10YR 5/1), very thick bedded; fine grained.

Sandstone: hard, pale-brown (IOYR 6/2), very thick bedded, fine-grained.

Sandstone: dolomitic, medium-hard, very pale brown (WYR 7/3), thick- bedded, fine-grained.

Franson Tongue of Park City Formation:Dolomite: hard, very pale orange

(10 YR 8/2), thick-bedded; aphanitic; contains some nodules and interbeds of dolomitic chert.

Limestone: hard, very pale brown (10 YR 7/2), very thick bedded; finely granular; irregular contact with bed below.

Lower member of Shedhorn Sandstone:Sandstone: hard, pale-brown (2.5F

5/2), very thick bedded; fine-grained; contains irregular lenses of sandy chert; contains phosphatic skeletal fragments.

Sandstone: hard, light-brownish-gray (WYR 6/1), very thick bedded; fine grained.

Rex Chert Tongue of Phosphoria Forma tion:

Chert: hard, pale-brown (10 YR 6/2), thick-bedded, contains a few inter beds of light-brownish-gray (10 YR 6/1), fine-grained sandstone.


(feet) (feet) SampleAcid Radiometric Chemical

P2O 5 insoluble «U U

2.5 128.2 WHW-3384 0.4 93.2 0.001 _.____-

2. 0 130. 2 3383 .7 93. 6 . 0005 0. 001

1. 7 131. 9

. 9 132. 8

. 7 133. 5

1. 7 135. 2

1. 1 136. 3

2. 5 149. 3

5. 0 154. 3

10. 0 164. 3

3. 8 168. 1

3. 4 171. 5

18. 7 190. 2

3. 1 193. 3

3. 2 196. 5

3382 18.5 41.3 .001 ____.-_

3381 27. 3 23. 0 . 008 . 008

3380 26. 7 20. 2 . 010 . 010

3379 31. 2 10. 5 009 . 009

3378 10. 4 43. 7 . 007 . 007

1 ^1. U

. 2

1. 6

1 9-L. £j

6. 0

m o. o

138. 0>

139. 6

140. 8

146. 8

3377 1. 8 75. 5 003 .___ __

3376 3.3 80.5 .003 _______

IIT^ 4. Q9 O 001


Warm Springs Creek, Mont., lot 1300 Continued

Bed

7.

M-6.

G-3_

2.

1.

Description

Lower member of Shedhorn Sandstone:Sandstone: hard, light-gray (N 7),

thick-bedded, medium-grained; con tains glauconite and phosphatic skeletal fragments; contains small black chert pebbles.

Dolomite: hard, light-brownish-gray (10 YR 6/1), thick-bedded; very fine grained; contains chert nodules 0.1 ft in diameter.

Meade Peak Phosphatic Shale Tongue of Phosphoria Formation:

Phosphorite: sandy, carbonatic, me dium-hard, medium-gray (.V 6), thin- bedded; nodular and medium-pelletal and oolitic; nodules average 0.05 ft in diameter.

Sandstone: phosphatic, hard, medium- gray (N 6), thick-bedded; fine-grain ed; apatite pellets are concentrated in laminae that constitute 20 percent of bed.

Phosphorite: sandy, hard, medium- gray (N 5), thick-bedded, apatite is me dium grained, oolitic; contains phos phatic fossil fragments.

Grandeur Member of Park City Formation, upper part:

Sandstone: hard, medium-gray (N 5), very thick bedded; very fine grained.

Sandstone: medium-hard, weak-yellow ish-orange (IOYR 8/4), thick-bedded, very fine grained.

Dolomite: hard, very pale brown (IQYR 7/2), thick-bedded; aphanitic; under lying rocks are covered. Fossil- colln. No. 11681.


Thickness (feet)

Cumulativethickness

(feet)

Uranium

0. 8 197.

Sample

WHW-750

Pa05Acid


eU U

3. 3 78. 3 0. 001 0. 001

197.

8 198. 7

1. 2 199. 9

2. 5 202. 4

9. 8 212. 2

15. 0 227. 2

744

743

19. 4

21.9

45. 4

39.3

004

004

005

004

Sliderock Mountain, Mont., lot 1301[Permian rocks measured on Sliderock Mountain, N^i sec. 25, T. 10 S., R. 4 W., Madison County, Mont., on overturned west limb of Ruby Valley syncline. Thrust fault

ing was recognized in older formations exposed up slope from outcrop of Permian rocks. Average strike is about north and the dip is about 40° W. Park City Formation and tongues of lower member of Shedhorn Sandstone measured from natural exposure and phosphatic shale members of Phosphoria Formation from hand trenches on spur between heads of South and Middle Forks of Fawn Creek. Tosi Chert Member of Phosphoria Formation measured from natural exposure in gully at head of Middle Fork of Fawn Creek. Measured by C. W. Tandy and E. R. Cressman and sampled by R. F. Gosman and W. J. Garmoe, in August 1949. Petrographic descriptions with binocular microscope by E. R. Cressman. Analyzed for PaOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]

Bed

To-76.

Us-75,

To-74.

73.

72.

Description

Tosi Chert Member of Phosphoria Forma tion; contains several thin tongues of Shedhorn Sandstone:

Mudstone: dolomitic, medium-hard, grayish-brown (10 YR 4/2), thin- bedded; contains glauconite. Over lying beds covered; top of bed To-76 may be Dinwoody contact.

Sandstone: glauconitic, medium-hard, light-brownish-gray (10 YR 5/1), thin-bedded, fine-grained; irregular contact with bed below.

Chert: brittle, light-brownish-gray (10 YR 5/1), thin-bedded; contains glauconite and scattered laminae and lenses of cherty siltstone; bed ding is undulant.

Chert: silty, brittle, brownish-gray (IQYR 4/1), thin-bedded; contains glauconite.

Chert: brittle, light-brownish-gray (10F.R 6/1), fissile; contains glauco nite; bedding is undulant; irregular contact with unit below.


Thickness (feet)

Cumulativethickness

(feet)

Uranium

22. 0

1. 0

8. 6

22.0

2. 7 24. 7

20. 6 45. 3

46.3

54.

P»0jAdd Radiometric Chemical

insoluble eU U


Sliderock Mountain, Mont., lot 1301 Continued

Bed Description

Tosi Chert Member of Phosphoria Forma tion; contains several thin tongues of Shedhorn Sandstone Continued

Us-71._____--_ Sandstone: hard, light-brownish-gray(1QYR 6/1), very thick bedded, fine grained; contains glauconite.

To-70_________ Chert: sandy, brittle, Light-brownish-gray (10YR 6/1), thin-bedded; con tains glauconite; sand is very fine; irregular contact with unit below.

69________. Dolomite: brittle, light-brownish-gray(10 YR 6/1), thick-bedded, aphanitic..

68.. _______ Chert: brittle, yellowish-gray (10 YR111), thin-bedded; contains glauco nite and irregular lenses and laminae of silty chert; contains several fine grained sandstone columns 0.2 to 0.3 ft in diameter and 0.5 to 0.6 ft long.

Us-67--_______ Sandstone: cherty, hard, pale-brown(2.5 F 5/2), thick-bedded, fine grained; contains glauconite.

To-66.-_------ Chert: hard, brownish-gray (10YR4/1), thin-bedded; contains glauco nite; irregular contact with unit below.

65-_--____- Chert: hard, medium-gray (N 6); contains approximately 25 percent of irregular lenses of hard, pale- brown (10 YR 5/3), very fine grained sandstone; lenses in upper 0.3 ft are phosphatic, and uppermost bedding surface is coated with layer 0.01 to 0.04 ft thick composed of phosphatic sandstone.

64. _._._.__ Chert: muddy, hard, black (N 2), thin- bedded; in fault contact with unit below.


Rt-63_________ Mudstone and phosphorite interbed-ded: soft brownish-black (10 YR 2/1) thin-bedded mudstone interbedded with medium-hard brownish-black (WYR 2/1) thin-bedded very finely pelletal phosphorite; irregular con tact with unit below.

62_________ Phosphorite: dolomitic, muddy, me dium-hard, brownish-black (107.fi 2/1), thin-bedded, very finely pel letal; irregular contact with unit below.

61 _--_-____ Mudstone: soft, brownish-black (10YR 2/1), thin-bedded; irregular contact with unit below.

60_________ Phosphorite: dolomitic, medium-hard,brownish-biack (10YR 2/1), thin- bedded, very finely pelletal.

59 _________ Dolomite: hard, light-brownish-gray(1QYR 5/1), thick-bedded, aphanitic.

58 _________ Mudstone: crumbly, brownish-gray(10YR 3/1); in fault contact with unit below.

57_________ Phosphorite: medium-hard, black (N 2),very finely pelletal; in fault contact with unit below.

56_._______ Phosphorite: calcareous, medium-hard,black (N 2), very finely pelletal; contains several small faults of un known displacement.



(feet) (feet)

Uranium

Sample Ps06Acid


eU U

2. 9

5.9

57. 8

58.5

59. 1

65.0

3. 5

4. 8

68. 5

73.3

60. 0 133. 3

6. 0 139. 3 CWT-692

3. 8 143. 1 691

143.6

144.2

145. 1

145. 7

146.

690

689

687

686

2. 4

146. 71

149. 1 ERG-685

1.0 87.5 0.001 _______

7. 3 51. 7 005 0.004

12.0 22. 5 .005 .005

2.9 53.3 .004 _______

22. 6 18. 3 008 .008

4.8 8.3 .003

12. 2 37. 1 007 .006

23. 4 14. 5 .009 . 009


Sliderock Mountain, Mont., lot 1301 ContinuedChemical analyses (percent)

Bed Description


Rt-55___---_-_ Mudstone: medium-hard, brownish-black (WYR 2/1), fissile.

54 __ ______ Phosphorite: medium-hard, brownish-black (WYR 2/1), thin-bedded, finely pelletal.

53-_------- Dolomite: hard, pale-brown (2.576/2),thick-bedded, aphanitic. Fossil- colln. No. 1 1672.

52_ ___ Mudstone: phosphatic, medium-hard,brownish-black (WYR 2/1), fissile; apatite is finely pelletal ; in fault con tact with unit below.

51--------- Phosphorite: soft, brownish-gray(WYR 4/1), fissile, finely pelletal.

50__ _______ Mudstone: soft, brownish-gray (WYR3/1), thin-bedded.

49 _----__-_ Mudstone: phosphatic, soft, brownish-gray (10 YR 4/1), fissile; apatite is very finely pelletal.

(48) __---_-- Covered: thickness is approximate. Fault is probably present in covered interval.

Lower tongue of Shedhorn Sandstone: Ls-47 _________ Sandstone : dolomitic, medium- hard,

light-brownish-gray (WYR 6/1), thick-bedded, fine-grained; contains phosphatic skeletal fragments.

46 _________ Sandstone: hard, yellowish-gray (10 YR8/1), thick-bedded, fine-grained; grades from bed below.

Franson Tongue of Park City Formation: F-45 ----_-____ Chert : hard, medium-gray (N 6) , thick-

bedded. 44-_---_____ Dolomite: medium-hard, light-

brownish-gray (10 YR 6/1), very fine grained.

43 __________ Dolomite: medium-hard, yellowish-white (WYR 9/1), thick-bedded, aphanitic.

42_ __ _______ Dolomite: medium-hard, yellowish-gray (WYR 7/1), thick-bedded, aphanitic; contains a few very irregular nodules of white (N 9) chert 0.1 to 0.8 ft in diameter.

41__________ Dolomite: medium-hard, yellowish-white (WYR 9/1), thick-bedded, aphanitic; contains a few very irregu lar nodules of white (N 9) chert 0.1 to 0.8 ft in diameter.

40-_________ Dolomite: medium-hard, yellowish-gray (WYR 7/1), thick-bedded, aphanitic ; contains a few very irregu lar nodules of white (N 9) chert 0.1 to 0.9 ft in diameter that are more numerous near base of unit; grades from unit below.

39__________ Dolomite: hard, very pale brown(WYR 7/2), thick-bedded, aphanitic; contains about 10 percent irregular chert nodules.

(38) ---_-_

R-37_

Rex Chert Member of Phosphoria Forma tion; contains several thin tongues of Shedhorn Sandstone:

Chert: brittle, yellowish-white (WYR 9/1), thin-bedded; contains much vuggy calcite; irregular contact with unit below.

UraniumCumulative

Thickness thickness (feet) (feet) Sample

Acid Padiometric insoluble eV

0. 5 149.

.2 149.8) ERG-684 21.6 20.4 0.010

2. 4 152. 2

1. 5 153. 7

6 154. 31

6 154. 9

4 155. 3

5. 0 160. 3

2. 6 162. 9

12. 5 175. 4

2. 2 177. 6

5. 0 182. 6

6. 0 188. 6

2. 4 191. 0

5. 8 196. 8

14. 2 211. 0

8. 7 219. 7

5. 5 225. 2

2. 7 227. 9

683

682 10. 2

12. 7

42. 0

681 13. 6 40. 7

001

006

007

ChemicalU

0.008

.006

. 006


Sliderock Mountain, Mont., lot 1301 ContinuedChemical analyses (percent)

Bed Description

Rex Chert Member of Phosphoria Forma tion; contains several thin tongues of Shedhorn Sandstone Continued

Ls-36_ __---.-_ Sandstone: hard, light-gray (N 7), thick-bedded, fine-grained; irregular contact with unit below.

R-35____---..- Chert: brittle, yellowish-white (1QYR9/1), thin-bedded; irregular contact with unit below.

Ls-34_ ________ Sandstone: cherty, hard, yellowish-gray(IQYR 8/1), very thick bedded, fine grained.

R-33-_________ Chert: dolomitic, brittle, yellowish-gray(10 YR 7/1), thick-bedded; bedding surfaces are undulant; irregular con tact with unit below.

Ls-32_ _______ Sandstone: hard, very pale brown (10 YR7/2), thick-bedded, fine-grained; con tains phosphatic skeletal fragments.

31________ Sandstone: medium-hard, light-brown ish-gray (IQYR 6/1), thick-bedded, fine-grained; contains glauconite and phosphatic skeletal fragments.

R-30--__------ Chert: sandy, brittle, very pale orange(10 YR 8/2), thin-bedded; contains glauconite and a few apatite pellets; grades from unit below.

29___------- Chert: brittle, yellowish-gray (IQYR7/1), thick-bedded; bedding surfaces are undulent; grades from unit below.

28-_-_------ Chert: brittle, medium-gray (N 5),thin-bedded.


M-27- ________ Phosphorite: silty, medium-hard,brownish-gray (10 YR 4/1), thin- bedded, finely pelletal.

26_-_----__ Siltstone: soft, light-yellowish-brown(IQYR 6/4), thin-bedded; irregular contact with unit below.

25 ___---___ Siltstone: medium-hard, pale-brown(10 YR 5/3), thick-bedded.

24_________ Sandstone: phosphatic, medium-hard,pale-brown (IQYR 5/3), thin-bedded,fine-grained; apatite is finely pelletal.

23___-_---- Sandstone: soft, dark-gray (N 3), veryfine grained.

22_________ Phosphorite: sandy, soft, dusky-brown(IQYR 2/2), medium-pelletal; sand is fine.

21_________ Sandstone: soft, dark-gray (N 3), veryfine grained.

20___-_---- Phosphorite: sandy, soft, dusky-brown(IQYR 2/2), coarsely pelletal; sand is very fine; irregular contact with unit below.

19_________ Sandstone: soft, dark-gray (N 3), veryfine grained.

18-__------ Phosphorite: soft, grayish-brown(IQYR 4/2), finely pelletal.

17 ____----_ Phosphorite: sandy, soft, grayish- brown (10 YR 4/2), corsely pelletal; sand is very fine; irregular contact with unit below.

16_----_--_ Phosphorite: hard, medium-gray (N 6),thin-bedded, coarsely pelletal.

Thickness (feet)

2.4

1. 5

1. 1

8.7

Q n

1.2

10. 6

1. 6

. 2

. 5

.3

.3

. 5

.3

1.3

. 5

. 2

. 5

thickness (feet)

230.3

231. 8

232. 9

241. 6

244. 6

244. 9

246. 1

256. 7

m Q

258. 5'

259. 0 '

259. 3^

O K.C\ O V

260. r260. 6

260. 8

262. 2

262. 71

262. 9 1

263.4

Uranium

Acid ffadiometric Chemical Sample P.Os insoluble eU U

CWT-699 14. 3 53. 0 0. 005 0. 005

698 5.7 72.7 .003 _______

697 18. 0 45. 5 . 006 . 007

696 26. 7 20. 2 . 009 . 008

695 14. 2 60. 0 . 005 . 005

694 26. 2 26. 0 . 008 . 008

1. 0 264. 4 693 34. 6 5. 0 Oil . 010


Sliderock Mountain, Mont., lot 1301 Continued

Bed

14.

13.

12.

11.

10.

Description

Grandeur Tongue of Park City Formation: Covered.._________________________Dolomite: hard, yellowish-gray (2.5Y

7/2), very thick bedded, aphanitic; unit is fractured and brecciated.

Dolomite: hard, dark-gray (N 4), thick-bedded, aphanitic.

Dolomite: hard, yellowish-gray (2.5Y 7/2), very thick bedded, aphanitic.

Sandstone: dolomitic, calcareous, hard, yellowish-gray (2.5 Y 7/2), very thick bedded, very fine grained.

Dolomite: calcareous, hard, yellowish- gray (10 YR 7/1), thick-bedded, aphanitic.

Limestone: hard, dark-gray (N 4), thin-bedded, aphanitic.

Dolomite: hard, very pale brown (10YR 7/2), thick-bedded, aphanitic. Fossil-colln. No. 11671.

Dolomite: hard, pale-brown (2.5Y 6/2), very thick bedded, aphanitic.

Sandstone: calcareous, hard, yellow ish-gray (2.5 Y 7/2), very thick bedded, very fine grained.

Dolomite: hard, pale-brown (2.5 Y 6/2), very thick bedded, aphanitic; contains many calcite veinlets.

Dolomite: hard, pale-brown (2.5 Y 6/2), very thick bedded, aphanitic.

Sandstone: dolomitic, hard, yellowish- gray (2.5 Y 7/2), thick-bedded, fine grained.

Dolomite: medium-hard, yellowish- gray (1QYR 8/1), thick-bedded, aphanitic.

Dolomite: medium-hard, medium-gray (N 6), thick-bedded, aphanitic. Un derlain by sandstone of the Quadrant Formation.

Thickness (feet)

35.017. 0

Cumulativethickness

(feet)

299.4316.4

. 8 317. 2

2. 0 319. 2

1. 7 320. 9

4. 7 325. 6

1. 0 326. 6

12. 0 338. 6

4. 4 343. 0

5. 2 348. 2

1. 2 349. 4

1. 2 350. 6

5. 8 356. 4

6. 7 363. 1

6. 8 369. 9


Uranium

Sample PjOsAcid

insolublePadiometric

eVChemical

U

West Fork of Blacktail Creek, Mont., lot 1302[Permian rocks measured near West Fork of Blacktail Creek, SE}4 see. 26, T. 12 S.,R. 6 W., Beaverhead County, Mont., on southeast limb of an anticline. Beds G-l through

F-42 measured in bulldozer trench near top of hill on northeast side of creek; beds Ls-44 through Us-87 measured in hand trench 1,500 ft farther south and about 250 ft up the slope from Blacktail road; rest of section measured from natural exposures near road. Beds strike N. 73° E. and dip 37° S. Section measured by E. R. Cressman C. W. Tandy, and W. H. Wilson and sampled by J. L. Elliott, B. K. Replogle, W. J. Garmore, and R. F. Gosman, in July 1949. Analyzed for PaOs and acid insoluble by U.S. Bur. of Mines and for other constituents by U.S. Geol. Survey]


Bed

D-105...

104.103.

102.

101.

To-100.

Description

Dinwoody Formation, lower part:Mudstone: calcareous, crumbly, light- 1. 2

brown (7.5YR 6/4), fissile.' Covered_______________________ 8. 0Limestone: clayey, crumbly, light- 1. 2

brown (7.SYR 6/4), fissile.Dolomite: hard, medium-gray (N&), .3

thin-bedded; aphanitic.Covered. Mudstone similar to that 7. 2

of bed D-105 was exposed by dig ging and probably constitutes the entire interval.


Limestone: sandy, brownish-gray 2. 7 (1QYR 4/1), thick-bedded; con tains 20 percent brachiopod shells, most of which are fragmental; sand is fine; grades from bed be low. Fossil-colln. No. 18577.

Cumulative Thkk- thickness

ness (feet) (feet)

Uranium

SampleAcid

insoluble OilOrganic matter

Radio- metric elT

Chemical U

2.7


West Fork of Blacktail Creek, Mont,, lot 1302 Continued

Bed Description


To-99_____- Dolomite: silty, medium-hard, light- brownish-gray (10 YR 6/1), thin- bedded, aphanitic; contains glauconite.

98_____ Dolomite: silty, medium-hard, pale- brown (2.5 Y 6/2), thin-bedded, aphanitic; contains glauconite. Fossil-colln. No. 11670.

97_____ Dolomite: cherty, silty, medium- hard, pale-brown (2.5 Y 5/2), thin- bedded, aphanitic. Fossil-colln. No. 11670.

96_____ Chert: dolomitic, hard, light-brown ish-gray (10 YR 5/1), thin-bedded.

95_---_ Chert: dolomitic, silty, medium-hard, pale-brown (2.5 Y 5/2), thin-bed ded.

94__-__ Dolomite: cherty, hard, medium- gray (N 5), very thick bedded, aphanitic.

93_- - _ _ Chert: dolomitic, silty, medium-hard, pale-brown (2.5 y 5/2), thin-bed ded.

92-__. Chert: hard, brownish-gray (10 YR 4/1), thick-bedded; contains sev eral indistinct laminae of very fine grained cherty sandstone; irregular contact with bed below.

Intertonguing Tosi Chert Member of Phosphoria Formation and upper mem ber of Shedhorn Sandstone:

Us-91 ______ Sandstone: cherty, hard, light-brown ish-gray (10 YR 6/1), thick-bedded, fine-grained; contains glauconite.

To-90___--_ Chert: dolomitic, hard, brownish- gray (10y«4/l), thin-bedded; ir regular contact with bed below.

Us-89--_--.- Sandstone: hard, brownish-gray (10 YR 4/1), thick-bedded, very fine grained; contains glauconite; contains several columnar bodies of black sandstone several milli meters in diameter and as much as a foot long that are nearly per pendicular to bedding; irregular contact with bed below.

To-88__--._ Chert: brittle, pale-brown (10 YR 6/2), thick-bedded; bedding sur faces are irregular.

Us-87------ Sandstone: cherty, hard, brownish- gray (10 YR 4/1), thick-bedded, very fine grained; contains glau conite; contains numerous very irregular patches of very pale brown (1QYR 7/2) cherty sand stone that is somewhat better ce mented than rest of unit; contains several long columnar bodies 2 mm in diameter of black sandstone that are perpendicular to the bed ding.

Retort Phosphatic Shale Member ofPhosphoria Formation:

Rt-86_--__- Phosphorite: cherty, medium-hard, light-brownish-gray (10 YR 6/1), medium-pelletal; contains glaucon ite; grades from bed below.

85______ Phosphorite: muddy, soft, brownish- gray (10 YR 3/1), thin-bedded, finely pelletal.


Cumulative Thick- thickness

ness (feet) (feet)

Uranium

SampleAcid

PsOj insolubk OilOrganic matter


1.0

2.4

12. 2

2.0

1.3

3.8

3.7

6.1

18.3

19.2

21.2

22.5

22.9

26. 7

2. 0 28. 7

5. 1 33.8

18. 0 51. 8

11.9 63.7

48. 0 111. 7

7 112.4 ERC-668 26.4 25.8 ___. _-.-_ 0.010 0.010

1. 0 113. 4 667 27.5 20.2 _.__ _____ .010 .010


West Fork of Blacktail Creek, Mont., lot 1302 Continued


Uranium

Bed Description

Retort Phosphatic Shale Member ofPhosphoria Formation Continued

Rt-84______ Phosphorite: muddy, soft, brownish- gray (10 YR 3/1), finely pelletal; pellets are concentrated in laminae 1 mm thick; grades from bed below. Fossil-colln. No. 11669.

83______ Mudstone: phosphatic, soft, brown ish-gray (WYR 3/1), thin-bedded; apatite is very finely pelletal; grades from bed below.

82------ Mudstone: dolomitic, medium-hard,light-brownish-gray (10 YR 6/1), thin-bedded.

81------ Mudstone: phosphatic, medium-hard,brownish-gray (10 YR 3/1), thin- bedded; apatite is very finely pel letal; grades from bed below.

80_ _ _ _- _ Mudstone: phosphatic, medium,hard, brownish-gray (10 YR 3/1), thin- bedded; apatite is very finely pel letal.

79______ Dolomite: muddy, medium-hard,light-yellowish-brown (10YR 6/4), aphanitic; grades from bed below. Fossil-colln. No. 11668.

78_ -____ Mudstone: dolomitic, soft, brownish- gray (10 YR 3/2).

77---___ Phosphorite(?): muddy, soft, brown ish-black (10 YR 2/1); bed is ex tensively sheared.

76_ _ - _ _ _ Mudstone: soft, brownish-gray (10 YR 3/2), thin-bedded; grades from bed below.

75______ Phosphorite: muddy, soft, brownish- gray (WYR 3/2), thin-bedded, very finely pelletal; grades from bed below.

74_-____ Mudstone: phosphatic(?), soft, pale- brown (10 YR 5/2), thin-bedded.

73_--__- Dolomite: phosphatic(?), medium- hard, pale-brown (10 YR 6/2), aphanitic; grades from bed below.

72_----_ Mudstone: phosphatic, soft, brown ish-gray (10YR 3/2), thin-bedded; grades from bed below.

71_-___- Mudstone: phosphatic, soft, brown ish-gray (WYR 3/2), thin-bedded; grades from bed below.

70_-_-__ Mudstone: phosphatic, crumbly, brownish-gray (WYR 3/2), thin- bedded; apatite is finely pelletal; grades from bed below.

69--____ Mudstone: phosphatic, soft, brown ish-gray (WYR 3/1), thin-bedded; grades from bed below.

68--_-__ Dolomite: medium-hard, brownish- gray (WYR 4/1), aphanitic.

67--__-_ Phosphorite: soft, brownish-gray (WYR 4/1), thin-bedded, medium- pelletal.

66_-_-__ Mudstone: medium-hard, brownish- gray (WYR 3/1) to grayish-brown (WYR 4/2), thin-bedded; grades from bed below.

65______ Mudstone: medium-hard, brownish- gray (WYR 3/1) to grayish-brown (WYR 4/2), thin-bedded; grades from bed below.

64___-__ Mudstone: soft, brownish-gray (WYR 3/1), thin-bedded; contains a few poorly defined laminae of fine grained apatite pellets.

Cumulative Thick- thickness

ness (feet) (feet)

2. 4

3. 3

. 8

1. 1

SampleAcid Organic Radio- Chemical

insoluble Oil matter metric eH U

2.7 116.1 ERG-666 16.3 37.8 ____ ----- 0.008 0.007

3. 8 119. 9 665 8.1 52.2 ____ ----- .006 .004

122. 3

125.6

664 5. 6 40. 8

663 8. 3 53. 7

. 002

. 004

3. 3 128. 9 662 10.6 49.3 ____ ----- .005 .005

2. 7 131. 6 CWT 661 3. 4 46. 7

660 8. 1 47. 2

659 4. 6 63. 4

658 16. 1 34. 6

. 5

.3

1.5

2.5

1. 9

1. 0

. 8

2.0

3. 0

132. 1}

132.4

133. 9

136.4

138. 3 X

139. 3

140. l'

142. 1

145. 1

2. 4 147. 5

148. 3

149. 4

2. 8 152. 2

3. 0 155. 2

1. 7 156. 9

ERG-669 1. 7 9. 8

652 26. 7 14. 2

651 4. 6 52. 7

650 2. 5 63. 2

649 4. 6 58. 0

. 001

.004 --_--

.003 -__-.

. 007 . 007

657 12.0 39.0 ____ -----

656 11.4 37.8 _.__ -----

655 8.1 52.2 __._ -----

654 7. 3 44. 8 1. 3 12. 01

653 10.2 46.6 ___- _____

. 005

. 004

. 004

.005

. 006

.002

. 009

.005

. 004

. 004

.005

. 005

. 005

. 010

. 006




Uranium

Thin ness (feet)

1.

1.

Bed Description

Retort Phosphatic Shale Member ofPhosphoria Formation Continued

Rt-63__-__- Phosphorite and mudstone, inter bedded: medium-hard brownish- gray (10 YR 3/1) thin-bedded finely pelletal phosphorite interbedded with medium-hard brownish-black (10 YR 2/1) phosphatic(?) mudstone.

62__-___ Phosphorite: medium-hard, brown ish-gray (10 YR 4/1), thick-bedded, finely pelletal and oolitic. Fossil- collection number 11667.

61__-__- Mudstone: phosphatic, soft, brown ish-black (WYR 2/1), thin-bedded; grades from bed below.

60____-_ Phosphorite: crumbly, light-brown ish-gray (WYR 6/1), thin-bedded, finely pelletal.

59______ Mudstone: phosphatic, soft, brown ish-black (WYR 2/1), thin-bedded; apatite is very finely pelletal.

58______ Dolomite: muddy, medium-hard,grayish-brown (2.5F 4/2), aphanitic.

57------ Mudstone: phosphatic, crumbly,brownish-gray (10 YR 3/1), thin- bedded; apatite is very finely pel letal.

56-_____ Dolomite: muddy, medium-hard, grayish-brown (2.5 F 4/2), aphanitic.

55______ Phosphorite: muddy, crumbly,brownish-gray (WYR 3/1), thin- bedded; very finely pelletal.

54__-___ Dolomite: medium-hard, pale-brown (10[YR 5/2), thick-bedded, aphanitic.

53_-____ Phosphorite: muddy, crumbly, yellowish-gray (WYR 8/1), thin- bedded, very finely pelletal. Fos- sil-colln. No. 11666.

52_____- Phosphorite: muddy, medium-hard, light-yellowish-brown (10FS6/4), thin-bedded, finely pelletal.

51_-____ Mudstone: medium-hard, yellowish- brown, thin-bedded.

50-_-___ Mudstone: soft, dark-brown, thin- bedded.

49_____- Mudstone: phosphatic, soft, dark- brown, thin-bedded.

48_ _-___ Mudstone: medium-hard, brownish- gray (10 YR 4/1). Fossil colln. No. 11665.

47-____- Mudstone: phosphatic, crumbly, grayish-brown (7.5YR 3/2), fissile; apatite is medium pelletal. Fossil- colln. No. 11665.

46______ Chert: brittle, brownish-gray (10 YR4/1); grades from bed below.

45______ Chert: hard, light-gray (N 7)_ _._ 3.Lower tongue of Shedhorn Sandstone:

Ls-44 __-_-_ Sandstone: medium-hard, light- yellowish-brown (WYR 6/4), very thick-bedded, fine-grained.

(43)_____ Covered. Comparison with neigh boring sections indicates that this interval is too thin. Either the thickness is in error or the con cealed beds are faulted.

Cumulativethickness

(feet)

2. 9

14. 0

Sample P.OsAcid

insoluble OilOrganic matter


0.9 157.8 ERG-648 21.6 26.2 ____ -____ 0.008 0.007

159. 1 647 30.6 11.3 .008

2.7 161.8 CWT-677 8.4 44.8 1.4 11.15 .006

1. 5

162. 5'

162. 9

164. 4

8 165. 2

1. 0 166. 2

8 167. 0

1. 0 168. 1

170.

170. 6

170. 8

171. 2

172. 0

8 172. 8

178. 7

192. 7

47. 0 239. 7

676 18. 6 27. 9

675 3. 1 28. 1

007

. 003

674 10. 3 35. 1 1. 3 10. 79 . 007

. 010

.004

.006

. 005

R7Q 19 91 9

672 13.8 34.2 ____ .

R71 19 17°

670 14. 7 36. 0 - - - - .

ERG-680 26.7 20.5 ____ .

_____ .002

.__._ .007

.__._ .002

.____ .007

._-__ .007

. 005

.005

. 006

679 12.9 50.5 ____ ----- -007 006

678 5 94.3 __-- ----- .0005 .000


West Fork of Blacktail Creek, Mont., lot 1 SOS ContinuedChemical analyses (percent)

Bed Description

Franson Tongue of Park City Formation: F-42_______ Dolomite: silty, hard, very pale

brown (10 YR 7/2), aphanitic.41_______ Dolomite: hard, light-brownish-gray

(IQYR 6/1), thick-bedded, apha nitic.

40__.____ Dolomite: muddy, hard, very pale brown (IQYR 7/2), thick-bedded, aphanitic.

39_______ Dolomite: sandy, medium-hard,yellowish-gray (2.57 7/2), apha nitic.

38_ ______ Dolomite: hard, yellowish - gray(IQYR 7/1), thick-bedded; irregu lar contact with bed below.


R-37_______ Chert: dolomitic, hard, brownish- gray (IQYR 3/1), thin-bedded, aphanitic; grades along bedding into hard very thick bedded brownish-gray (WYR 3/1) chert.

36_______ Dolomite: silty, medium-hard, light- brownish-gray (IQYR 5/1), thin- bedded, aphanitic; irregular con tact with bed below.

35_______ Dolomite: silty, hard, light-brown ish-gray (IQYR 5/1), thick,bedded.

34________ Dolomite: cherty, imiddy, brittle,medium-gray (N 5), thick-bedded, aphanitic; grades from bed below.

33_ _ ____ Covered.________________________32_______ Dolomite: muddy, hard, light-

brownish-gray (\.QYR 5/1), thick- bedded, aphanitic.

31_______ Chert: dolomitic, hard, medium-gray(N 5), thick-bedded.

(30)______ Covered_____ ____________________29_______ Chert: hard, pale-brown (2.5F 5/2),

thin-bedded.28 ____ Chert: silty, phosphatic(?), hard,

pale-brown (IQYR 5/2), thin- bedded.

27_______ Chert: hard, pale-brown (2.575/2),thin-bedded; grades from bed below.

26_______ Chert: brittle, light-brownish-gray(10 YR 5/1), thick-bedded.

25_______ Chert: silty, medium-hard, grayish- brown (7.5 YR 4/2), thin-bedded.

24 ____ Chert: brittle, light-brownish-gray (IQYR 5/1), thin-bedded; irregular contact with bed below; cut by several small faults of unknown displacement.

23_______ Chert: silty, crumbly, dusky-brown(IQYR 2/2), thick-bedded; grades from bed below.

22_______ Chert: soft light-brown (7.5YR 5/6)chert interbedded with medium- hard dark-gray (N 3) chert.


M-21______ Mudstone: soft, pale-brown (7.5 YR6/2), thick-bedded; contains thin layer of phosphorite less than 0.1 ft thick at top.


4. 8 244. 5

1. 3 245. 8

2. 0 247. 8

9 248. 7

1. 7 250. 4

12. 7 263. 1

8 263.9

1. 2 265. 1

4. 2 269. 3

4. 5 2. 1

9. 5 13.0

273.8275.9

1. 4 277. 3

286.8299.8

1. 3 301. 1

1. 0 302. 1

6. 7 308. 8

1. 2 310. 0

17. 3 327. 3

327.8

Uranium

SampleAcid

insoluble OHOrganic matter

Radio- metric eV

Chemical U

ERG-646 0.3 94.0 -___ ----- 0.001

1. 1 328. 9 WHW-645

1. 8 330. 7 644

2 95.2

6 87.0

0005

003 0. 001



505


Bed Description

Meade Peak Phosphatic Shale Member ofPhosphoria Formation Continued

M 20______ Mudstone: soft weak-orange (7.5 YR7/6) thin-bedded mudstone interbedded with soft black (N 2) thin- bedded phosphatic mudstone; apa tite is very finely pelletal.

19______ Mudstone: soft, light-brown (7.5YR5/6>, thick-bedded.

18______ Phosphorite: muddy, soft, black(N 2), thin-bedded, medium-pelletal.

17______ Phosphorite: silty, soft, black (AT 2),thick-bedded, finely pelletal.

16______ Mudstone: plastic, medium-yellow ish-brown (10 YR 4/4), thick-bed ded.

15______ Phosphorite: muddy, soft, black(N 2), thin-bedded, medium- pelletal.

14______ Mudstone: crumbly, light-brown(7.5 YR 5/6); grades from bed below (Analysis may be in error).

13______ Mudstone: muddv, phosphatic, clas tic, brownish-black (10 YR 2/1); apatite is medium pelletal.

12______ Phosphorite: muddy, black (N 1),crumbly, finely pelletal.

!]____-_ Phosphorite: sandy, cherty, me dium-hard, brownish-gray (10 YR 3/1), thin-bedded, finely pelletal; contains phosphatic skeletal frag ments. Fossil-colln. No. 11664.

10____-_ Sandstone: phosphatic, medium- hard, dusky-brown (10 YR 2/2), thick-bedded, very fine grained; contains phosphatic skeletal frag ments. Fossil-colln. No. 11664.

Grandeur Tongue of Park City Forma tion, upper part:

G 9___-_-__ Mudstone: cherty, crumbly, weak- yellowish-orange (WYR 7/6).

8__-____- Dolomite: crumbly, moderate-yel lowish-brown (10 YR 5/6) thin- bedded, aphanitic.

7________ Dolomite: silty, medium-hard, weak- yellowish-orange (2.5 Y 7/4), thick- bedded, aphanitic.

6________ Sandstone: dolomitic, medium-hard,weak-yellowish-orange (2.5F 7/4), very fine grained.

5---____- Dolomite: soft, weak-yellowish- orange (2.5F 8/4), aphanitic.

4._______ Dolomite: silty, medium-hard, weak- yellowish-orange (2.5F 7/4), aph anitic.

3----_-_- Dolomite: silty, medium-hard, yel lowish-gray (2.5y 7/2), thin-bed ded, aphanitic.

2_ _______ Sandstone: crumbly, weak-yellow ish-orange (10yR 7/6), fine grained.

l--_--___ Dolomite: silty, medium-hard, yel lowish-gray (2.5 y 7/2), thin-bed ded, aphanitic. Underlying beds are covered.


Uranium

Sample P.O5Acid

insolubleOrganic Padio- Chemical

Oil matter metric e~U U

1.5 332.2 WHW-643 6.5 69.5 ____

1. 9 334. 1

. 9 335.

4 335. 4

3 335. 7

336. 2

8 337.

. 7 338. 3

1. 1 339. 4l

339. 7

3. 4 343. 1

2. 7 345. 8

6. 0 351. 8

5. 6 357. 4

2 2 359. 6

2. 9 362. 5

4. 5 367. 0

5. 0 372. 0

15. 0 387. 0

642 2. 3 81. 3

641 12. 0 52. 5

0.004

002

. 005 0. 004

640 20.3 26.3 1.3 10.79 .011

6 336. 8 ERG-639 3. 2 71. 5 005

Oil

003

638 19.8 28.8 ____ _____ .009 .008

637 19. 4 41. 0 . 008 .007


Alpine Creek, Mont., lot 1807

[Permian rocks measured in southeast-facing slope at head of Alpine Creek, N}4 sec. 26, T. 10 S., K. 2 W., Madison County, Mont., on gently dipping east limb of Kuby Vallej syncline. Retort Phosphatic Shale Member of Phosphoria Formation measured and sampled in hand trench; all others from natural exposure. Beds strike N. 5° E. and dip 8° W. Section measured by E. R. Cressman, W. H. Wilson, and R. L. Jones and sampled by W. J. Qarmoe and J. L. Elliott, in August 1949. Analyzed for PjOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

(50).

Us-49-

48.

(47). 46.

45.

44.

To-43.

42.

41.

(40). 39.

38_

Rt-37_

36_

35.

Description

Upper Tongue of Shedhorn Sandstone:Beds overlying Us-49 are covered;

thickness to contact with Dinwoody estimated.

Sandstone: dolomitic, medium-hard, very pale orange (7.5YR 8/2), thin- bedded, cross-bedded, fine-grained; contains about 15 percent of dolo mitic shell fragments; contains a few lenses 0.01 to 0.05 ft by 0.03 to 0.5 ft of dolomite, some of which appear to be clastic. Fossil-colln. No. 11689.

Dolomite: cherty, medium-hard, very pale orange (7.5YR 8/2), thick- bedded; approximately half of bed is composed of silicified shell frag ments. Fossil-colln. Nos. 11688 and 18580.

Covered._ _________________________Dolomite: sandy, medium-hard, very

pale orange (7.5YR 8/2), thick- bedded; dolomite consists largely of shell fragments; sand is fine. Fossil- colln. No. 11687.

Sandstone: medium-hard, light-gray (N 7), very fine grained.

Sandstone: medium-hard, light-gray (N 7), very fine grained; contains numerous roughly cylindrical col umns 0.1 ft to 0.3 ft in diameter of hard pinkish-gray very fine grained cherty sandstone arranged perpen dicular to bedding.


Sandstone and chert: medium-hard light-gray (N 7) sandstone and hard light-brownish-gray (WYR 6/1) sandy chert; sand is very fine; grades from chert containing 25 percent irregular bodies of sandstone at base to sandstone containing 30 to 40 percent irregular bodies of chert at top; grades from bed below.

Chert: hard, light-brownish-gray (WYR 6/1), very thick bedded; con tains irregular bodies of very fine grained sandstone at top; grades from bed below.

Chert: brittle, light-brownish-gray (WYR 6/1), thin-bedded; bedding surfaces are undulant.

Covered._ _________________________Chert: brittle, brownish-gray (10 YR

3/1), thin-bedded.Similar to bed To-39_______---_---_


Phosphorite: muddy, soft, light-brown (7.5 YR 5/4), thick-bedded, very finely pelletal.

Phosphorite: medium-hard, light-gray (N 7), thin-bedded, very finely pelletal.

Mudstone: plastic, pale-brown (WYR 5/3).

UraniumCumulative

Thickness thickness (feet) (feet)

10. 0

4. 9

4. 2

2.0 3. 0

14. 0

4. 8

8.0

36. 5

11. 5

9. 5 5. 9

SampleAcid


U

10.0

14.9

19. 1

21. 124 1

38. 1

42. 9

50.9

87. 4

98.9

108.4114. 3

2. 4 116. 7 WHW-3394 0. 9 90. 6 0. 001

117. 1

117.8

1. 8 119. 6

3393

3392

30. 5 13. 17

4.6 64. 6

. 009

.004

0. 001

. 009

.003


Alpine Creek, Mont., lot 1307 Continued

Bed Description


Rt-34________ Dolomite: medium-hard, pale-brown(10 YR 5/3), fissile, aphanitic.

33________ Phosphorite: calcareous, cherty, me dium-hard, light-gray (N 7), thin- bedded, very finely pelletal.

32________ Mudstone: phosphatic, medium-hard,moderate-yellowish-brown (IOYR 5/6), thin-bedded.

31________ Chert: brittle, brownish-gray (10 YR3/1), thick-bedded; contains phos phatic skeletal fragments; grades from bed below.

30________ Chert: hard, light-brownish-gray(IOYR 6/1), very thick bedded; grades from bed below.

Lower tongue of Shedhorn Sandstone: Ls-29_ _______ Sandstone: hard, light-gray (N 7),

thick-bedded, fine-grained; contains phosphatic skeletal fragments; grades from bed below.

28 ________ Sandstone: carbonatic, hard, light- gray (N 7) to pale-brown (7.5 YR 6/2), thick-bedded, fine-grained; con tains phosphatic skeletal fragments, fragments of pelletal phosphorites, dolomitic phosphorites, and bryozoan fragments replaced by apatite; contains dolomite pebbles, 3 mm in diameter at base.

Franson Tongue of Park City Formation: F-27_________ Dolomite: medium-hard, pale-brown

(IOYR 6/2), thick-bedded, aphanitic; grades from bed below.

26_________ Dolomite: sandy, hard, weak-yellowish- orange (IOYR 8/4), thick-bedded, aphanitic; sand is very fine.

25_________ Dolomite: hard, very pale brown(10 YR 7/3), thick-bedded, aphanitic; grades from bed below.

Lower tongue of Shedhorn Sandstone; con tains thin bed of Rex Chert Member of Phosphoria Formation:

Ls-24-_______ Sandstone: dolomitic, medium-hard,weak-yellowish-orange (IOYR 8/4), thin-bedded, aphanitic; sand is fine. Fossil-colln. No. 18579.

R-23_________ Chert: hard, very pale brown (IOYR7/2), very thick bedded.

Ls-22________ Sandstone: hard, yellowish-gray (IOYR7/1), thick-bedded, fine-grained; con tains apatite pellets and skeletal fragments and fragments of phos phorite; basal 0.2 ft contains chert nodules 0.15 ft in diameter.

21------__ Dolomite: hard, light-brownish-gray(IOYR 6/1), thick-bedded, aphanitic; penetrated by thin pencillike stringers of fine-grained to dolomitic sandstone of overlying bed; contains numerous chert nodules 0.1 to 0.2 ft in diameter in basal 0.2 ft of bed.

20________ Sandstone: hard, light-gray (N 7),very thick bedded, fine-grained: con tains apatite pellets and skeletal fragments; grades from bed below.

19________ Sandstone: phosphatic, conglomeratic,hard, light-gray (N 7), thick-bedded, fine-grained; apatite is both pelletal and skeletal; pebbles average about 16 mm in diameter and are composed mostly of chert and dolomite. Fossil- colln. No. 11686.


Thickness (feet)

Cumulativethickness(feet)

Uranium

0. 8 120.

121.

1. 0 122. 1

3. 7 125. 8

6 126. 4

6. 7 133. 1

3. 0 136. 1

5. 2 141. 3

3. 6 144. 9

6. 8 151. 7

3. 2 154. 9

2. 2 157. 7

1. 7 158. 8

2. 3 161. 1

9 162. 0

SampleAct, Radiometric Chemical

eV U

120. 6} WHW-3391

3390

3389

2. 6

12. 1

5.6

29. 4 0. 002

52. 5

79.9

005

003

0. 002

004

003

3388

3387

2.3 90. 0

53. 7

000

002

002

002


Alpine Creek, Mont., lot 1307 Continued


Bed Description


M-18_________ Phosphate rock: conglomeratic, sandy,hard, light-gray (N 7), thick-bedded, skeletal; pebbles average 3 mm in diameter, are composed mostly of chert and dolomite and are con centrated in layers. Fossil-colln. No. 11685.

Grandeur Tongue of Park City Formation: G-17__________ Dolomite: hard, yellowish-gray (10 YR

7/1), thick-bedded, aphanitic; con tains a few chert nodules 5 mm in diameter.

16._________ Dolomite: hard, light-yellowish-brown(IOYR 6/4), thick-bedded, aphanitic.

15__________ Dolomite: hard, yellowish-gray (2.5F7/2), thick-bedded, cross-bedded, granular; irregular contact with bed below.

14__________ Dolomite: hard, very pale brown(10 YR 7/2), thick-bedded, granular; grades from bed below.

13__________ Dolomite: hard, very pale brown(10 YR 7/3), thick-bedded, crossbedded, very fine grained; contains a few chert nodules averaging 25 mm in diameter.

12._________ Dolomite: hard, yellowish-gray (IOYR8/1), thick-bedded, granular.

11__________ Dolomite: silty, hard, yellowish-gray(IOYR 8/1), thick-bedded, aphantic.

10-_ ---_____ Sandstone: dolomitic, hard, white (N 9), thick-bedded, fine-grained; grades from bed below.

9___________ Dolomite: sandy, hard, light-gray (N8), thin-bedded, cross-bedded, aph anitic; sand is very fine; contains subangular fragments of sandy dolo mite 1 mm in diameter and a few small chert nodules that replace both dolomite matrix and sandy dolomite fragments.

8___________ Dolomite: silty, hard, light-gray (N 8),very thick bedded, very fine grained.

7___________ Sandstone: dolomitic, hard, light-gray(N 8), very thick bedded, fine grained; 50 percent of bed at base grading to 20 percent of bed at top consists of pebbles averaging 20 mm in diameter of aphanitic dolomite; irregular contact with bed below.

6___ ________ Dolomite: medium-hard, light-gray(N 8), massive; consists of subangu lar to subrounded pebbles of aphanit ic dolomite averaging 8 to 10 mm in diameter, cemented by aphanitic dolomite; grades from bed below.

5. ________ Dolomite: medium-hard, light-gray(N 8) to white (N 9), thick-bedded, aphanitic; grades from bed below.

4. __________ Dolomite: sandy, hard, light-gray(N 8), very thick bedded; composed of subangular to subrounded pebbels of aphanitic dolomite (50 percent) in sandy dolomite matrix; sand is very fine.


(feet) (feet)

Uranium


insoluble eU U

1. 1 163. 1 WHW-3386 1. 1 19. 1 0. 007 0.006

2. 9 166. 0

2. 9 168. 9

3. 3 172. 2

3. 8 176. 0

. 8 176. 8

2. 2 179. 0

2. 8 181. 8

. 8 182. 6

. 9 183. 5

1. 7 185. 2

2. 4 187. 6

2. 0 189. 6

2. 8 192. 4

2. 6 195. 0


Alpine Creek, Mont., lot 1307 ContinuedChemical analyses (percent)

Bed

G-3.

Q-l.

Description


Dolomite; medium-hard, light-gray (N 8) to white (JV9), thick-bedded, aphanitic.

Dolomite: sandy, medium-hard, white (N 9), thick-bedded; sand is very very fine.

Quadrant Formation, uppermost bed:Sandstone: dolomitic, hard, white (N

9), very thick bedded; sand is fine.


Uranium

(feet) (feet) SampleAcid Radiometric Chemical

insoluble eU U

15. 5 210. 5

. 3 210. 8

5. 4 216. 2

Canyon Camp, Mont., lot 1811

[Permian rocks measured at Canyon Camp, Ruby River Canyon, NE}4 sec. 18, T. 9 S., R. 3 W., Madison County, Mont., on overturned west limb of Ruby Valley syncllne. Beds strike N. 10° W. and dip 50° W. Beds O-l through R-31 measured from natural exposures on north side of canyon 300 ft above ri^er; rest of section measured on south side of canyon, beds F-33 through Rt-48 and To-80 through D-99 from natural exposures, and beds Rt 49 through To-79 irom prospect trench. Measured by C. W. Tandy, R. S. Jones, E. R. Cressman, R. F. Oosman, and W. J. Garmoe and sampled by Gosman and Garmoe, in August 1949. Analyzed for PaOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

D-99.

98.

To-97.

Us-96.

95.

94.

93.

92_

To-9l_

90.

89.

Us-88.



Din woody Formation, basal beds:Limestone: hard, light-brownish-gray 1. 8 ______

(10YR 5/1), thin-bedded, skeletal.Covered; probably underlain by cal- 15. 0 ______

careous mudstone.Tosi Chert Member of Phosphoria Forma

tion:Mudstone: cherty, dolomitic, hard, 12. 3

pale-brown (10 YR 5/2), thin-bedded; contains glauconite.

Upper tongue of Shedhorn Sandstone:Sandstone: cherty, hard, light-brown- . 2

ish-gray (IOYR 5/1), thin-bedded, fine-grained; contains glauconite.

Chert: dolomitic(?), medium-hard, . 3 grayish-brown (7.5YR 4/2), thin- bedded; contains glauconite.

Sandstone: cherty, hard, light-brown- . 4 ish-gray (WYR 5/1), thin-bedded, fine-grained; contains glauconite; ir regular contact with bed below.

Chert: hard, light-brownish-gray 2. 7 (WYR 5/1), thick-bedded; contains glauconite; irregular contact with bed below.

Sandstone: cherty, medium-hard, very 4. 2 pale brown (10 YR 7/2), thick-bed ded, very fine grained; contains glauconite.


Chert: hard, medium-gray (N 5), 12. 8 32. 9 thick-bedded; contains glauconite.

Chert: dolomitic, hard, light-brownish- 6. 0 gray (IOYR 5/1), thick-bedded; con tains glauconite and numerous lenses of very fine grained cherty sandstone; irregular contact with bed below.

Chert and dolomite, interbedded: dolo- 2. 1 mitic hard medium-gray (N 5) chert interbedded with medium- hard light-brownish-gray (IOYR 6/1) dolomite; contains glauconite and phosphatic skeletal fragments; irreg ular contact with bed below.

Upper tongue of Shedhorn Sandstone:Sandstone: cherty, medium-hard, gray- 2. 0

ish-brown (IOYR 4/2), thin-bedded, fine-grained; contains glauconite and phosphatic skeletal fragments; irreg ular contact with bed below.

Uranium

SampleAcid


eV U

12. 3

12. 5

12. 8

13. 2

15. 9

20. 1

38.9

41. 0

43. 0

709-931 O-64 16


Canyon Camp, Mont., lot 1811 ContinuedChemical analyses (percent)

Us-87

86

To-85_

84_

83

82

81.

80-

79.78_

77-

76_

75_

74

Rt-73

72_

71-

70_

69-

68

67

66-

65-

64.

63.

62.

61-

60.

Bed Description

Upper tongue of Shedhorn Sandstone Con.Chert: hard, medium-gray (N 5), thin-

bedded; contains glauconite; irregu lar contact with bed below.

Sandstone: cherty, hard, light-brown ish-gray (10YR 6/1), very thick bedded, very fine grained; contains glauconite; irregular contact with bed below.


Chert: sandy, hard, light-gray (N 7), thick-bedded, very fine grained; sepa rated from underlying bed by fault of unknown displacement.

Chert: hard, dark-gray (N 4), thin- bedded; thickness is approximate; separated from underlying bed by fault of unknown displacement.

Chert: hard, dark-gray (N 4), thin- bedded.

Chert: dolomitic, hard, dark-gray (N 4), thin-bedded; separated from underlying bed by fault of unknown displacement.

Chert: dolomitic, hard, medium-gray (AT 5), thick-bedded.

Chert: dolomitic, hard, dark-gray (N 4), thin-bedded.

Chert: hard, black (N2), thin-bedded-Chert: hard, dark-gray (N 3), thin-

bedded.Chert: hard, dark-gray (N 3), thin-

bedded.Chert: muddy, hard, dark-gray (N 3),

thin-bedded.Chert: dolomitic, hard, dark-gray (N3),

thin-bedded.Chert: dolomitic, muddy, hard, brown

ish-gray (10 YR 3/1), thin-bedded. Retort Phosphatic Shale Member of Phos

phoria Formation:Mudstone: cherty medium-hard,

brownish-gray (10YR 3/1), thin- bedded.

Mudstone: medium-hard, brownish- black (10 YR 2/1), thin-bedded.

Mudstone: soft, dark-brown (10 YR 3/2), thin-bedded.



Mudstone: crumbly, brownish-black black (10 YR 2/1), thin-bedded. 9

Phosphorite: hard, brownish-black (10 YR 2/1), thick-bedded, medium- pell etal and oolitic.

Phosphorite: hard, black (AT 2), thick- bedded, finely pelletal.

Dolmite: hard, brownish-black (10YR2/1), thick-bedded, aphanitic.

Mudstone: medium-hard, brownish- (10Ffl2/l), thin-bedded.

Phosphorite: hard, black (N 2), thin- medium- pelletal.

Phosphorite: muddy, medium-hard, black (N 2), thin-bedded, finely pelletal.

soft, black (N 1), thin-Mudstone: bedded.

Mudstone: bedded.

soft, black (N 2), thin-


(feet) (feet)

1. 6 44. 6

23. 3 67. 9

14.0 81.9

15. 0 96. 9

1. 7 98. 6

3. 0 101. 6

1. 5 103. 1

. 4 103. 5

.5 104. 0 2. 0 106. 0

1.

1.

1.

2.

2.

1.

1.

1.

1.

2.

1.

1.

5 106. 5

1 107. 6

4 109. 0

2 110. 2

3 112. 5

5 115. 0'

2 115. 2

5 115. 7

9 116. 6

8 117. 4

4 118. 8

1 119. 9^

9 120. 8

5 122. 3

6 123. 9

6 126. 5

1 127. 6

6 129. 2

Sample

RSJ-725 724

723

722

721

720

719

718

717

716

715

714

713

CWT-712

711

710

Uraniiim

Acid Radiometric Chemical PaOs insoluble eV U

0.

1.

3.

2.

6.

25.

17.

15.

15.

5.

7.

8 8

6

3

8

5

0

8

3

9

5

6

5

2

8

4

80. 5 81. 7

85. 1

84. 4

76. 8

57. 3

69- 3

60.6

70.0

50.8

11.3

5.8

33.6

27. 2

41.2

38.8

0. 001 . 001

. 001

. 002

. 002

. 000

. 002

. 003

. 002

. 005

. 008

. 008

. 008

. 008

. 007

. 007

0. 001 . 001

. 001

. 001

. 002

. 001

. 003

. 002

. 001

. 004

. 009

. 006

. 007

. 009

. 005

. 007



0. 6 129. 8 CWT-709




Rt-59__.______ Mudstone: medium-hard, black (N 2),thin-bedded; shear zone 0.1 ft thickat top.

58_________ Mudstone: medium-hard, black (A^ 2),thin-bedded.

57_________ Dolomite: hard, light-brownish-gray(10 YR 5/1), thick-bedded, aphanitic.

56_________ Mudstone: medium-hard, black (N 2),thin-bedded.

55 _________ Phosphorite: medium-hard, black(N 2), thin-bedded, medium-pelletal.Fossil-colln. No. 11684.

54__ _______ Mudstone: dolomitic, hard, light- 3.0 138.5brownish-gray (WYR 5/1), thin- bedded.

53_________ Mudstone: phosphatic, medium-hard, . 7 139. 2brownish-gray (WYR 3/1), thin- bedded.

52_________ Phosphorite: calcareous, medium-hard, 1. 4 140. 6black (N 2), thin-bedded, medium-pellatal and oolitic.

51 _________ Mudstone: medium-hard, brownish- 1. 5 142. 1gray (10 YR 3/1), thin-bedded.

50_________ Mudstone: soft, dark-gray (AT 3), thin- . 9 143. 0bedded. Fossil-colln. No. 11683.

49_________ Chert: hard, brownish-gray (WYR .6 143.63/1), thin-bedded.

48_________ Sandstone: carbonatic, hard, light- 1. 1 144. 7brownish-gray (10 YR 5/1), verythick bedded, fine-grained; irregularcontact with bed below.

47_________ Chert: sandy, hard, medium-gray 2. 0 146. 7(N 5), very thick bedded.

46_________ Chert: sandy, hard, medium-gray 1. 2 147. 9(N 5), very thick bedded; sand isvery fine.

45_________ Chert: sandy, hard, dark-gray (N 3), 2. 2 150. 1very thick bedded; sand is very fine.

Franson Tongue of Park City Formation: F-44__________ Dolomite: sandy, hard, medium-gray 1. 8 151. 9

(N 6), very thick bedded, aphanitic;contains a few small chert nodules.

43__________ Dolomite: silty, hard, medium-gray 1. 3 153. 2(N 6), very thick bedded, very finelygranular.

42__________ Dolomite and chert, interbedded: hard 6.4 159.6medium-gray (N 5) thick-beddedaphanitic sandy dolomite interbedded with hard dark-gray (N 3)thick-bedded chert.

41__________ Dolomite: hard, yellowish-gray (10\YR 14.3 173.97/1), very thick bedded, aphanitic;irregular contact with bed below.

40_ _________ Dolomite: hard, light-brownish-gray 1. 7 175. 6(WYR 5/1), very thick bedded,finely granular.

39__________ Chert: hard, mottled light-gray (N 8) .5 176.1and dark-gray (N 3), thick-bedded.

38._________ Dolomite: silty, hard, medium-gray 4.3 180.4(N 5), very thick bedded, aphanitic;irregular contact with bed below.

37__________ Dolomite: hard, light-brownish-gray 2. 1 182. 5(WYR 5/1), very thick bedded,aphanitic.

36. _________ Dolomite: sandy, medium-hard, light- 4.5 187.0yellow (2.5F9/6), very thick bedded;sand is fine.

35_ _________ Dolomite: medium-hard, medium-gray 8.2 195.2(N 6), very thick bedded, aphanitic;irregular contact with bed below.

34_ _________ Chert: hard, dark-gray (N 3), very 3.0 198.2thick bedded.

Uranium


insoluble e\J U

6. 1 44. 0 0. 007 0. 006

. 9

1. 6

1. 2

2. 0

130. 7

132. 3

133. 5

135. 5

708

707

706

705

6. 4

1.3

6. 8

23. 9

46. 0

8.7

40. 7

11. 8

. 007

. 001

. 005

. 008

. 005

. 001

. 005

. 009

704

703

702

701

700

1. 6

10. 0

22. 9

2.7

6. 5

43. 2

47. 0

11. 6

67. 8

71. 3

002

005

Oil

003

004

. 001

. 005

. 012

. 002

. 004



Bed

F-33_

(32).

R-31.

30.

29.

28.

27_.

26__

25

24

23

22

21

M-20._

19_.

18..

17..

16-.

15.-

12.

11.

10.

Description


Dolomite: hard, yellowish-gray (10YR 7/1), very thick bedded, aphanitic.

Covered: an unknown thickness of beds intervenes between R-31 on north side and F-33 on south side of can yon.


Chert: hard, pale-brown (10 YR 6/2), thick-bedded.

Dolomite: hard, light-brownish-gray (10 YR 5/1), thick-bedded, aphanitic; grades from bed below.

Chert: sandy, hard, medium-gray (N 5), thick-bedded; irregular con tact with bed below.

Sandstone: cherty, hard, dark-gray (N 4), thick-bedded, fine-grained; contains a few phosphorite pebbles or nodules as much as 3 mm in diam eter; irregular contact with bed below.

Dolomite: cherty, sandy, hard, light- brownish-gray (10 YR 6/1), thick- bedded.

Mudstone: medium-hard, dusky-brown (10YR 2/2), fissile.

Chert: hard, brownish-gray (10 YR 3/1), thin-bedded.

Siltstone: cherty, hard, grayish-brown (10 YR 2/3), thin-bedded; contains glauconite.


Chert: hard, brownish-gray (10 YR 4/1), fissile.

Chert: hard, black (N 2), thin bedded. _ Meade Peak Phosphatic Shale Member of

Phosphoria Formation:Phosphorite: hard, brownish-black

(IOYR 2/1), thin-bedded, medium- pelletal. Fossil-colln. No. 11682.

Limestone: medium-hard, white (N9), thick-bedded, aphanitic.

Chert: brittle, brownish-gray (1QYR 3/1), thin-bedded.

Limestone: medium-hard, yellowish- white (1QYR 9/1), thin-bedded, aphanitic.

Chert: brittle, brownish-gray (10 YR 3/1), thin-bedded.

Phosphorite: sandy, hard, brownish- gray (IOYR 3/1), .thick-bedded, medium-pelletal and oolitic; contains phosphatic skeletal fragments and chert and phosphorite pebbles as much as 0.1 ft in diameter. Analysis may be in error.

Grandeur Tongue of Park City Formation, upper part:

Dolomite: medium-hard, light-gray (N 8), very thick bedded, aphanitic.

Chert: dolomitic, hard, light-brownish- gray (10 YR 6/1), thick-bedded.

Sandstone: hard, dark-gray (N 4), thin- bedded, fine-grained.

Dolomite: hard, yellowish-gray (1QYR 7/1), very thick bedded, aphanitic; contains a few chert nodules 5 to 20 mm in diameter.

Chert: dolomitic, very pale brown (1QYR 7/2), thin-bedded.

Thickness (feet)

14. 3

1 9

. 6

1. 1

g

1. 4

. 6

. 8

4 7

5. 0

. 3

.4

.5

1. 0

. 5

. 1

. 2

. 5

1. 7

.3

. 1

1. 4

. 3

thickness (feet)

212. 5

213. 8

214 4

215. 5

216. 4

217. 8

m A

219. 2

OOQ Q

228. 9

229. 21

229. 6J

230. 1

231. 1

231. &

231. 7

231. 9

232. 4

234. I

234. 4

234. 5

OQK Q

236. 2

Uranium

Acid Radiometric Chemical Sample PtOt insoluble ell II

ERG-732 0. 9 75. 4 0. 000 0. 001

731 1. 1 85. 8 . 000 . 001

730 27. 0 18. 7 . 007 . 008

729 3. 0 8. 8 . 000 . 002

728 2. 5 77. 7 . 001 . 002

727 5. 6 15. 8 . 007 . 008

726 1. 2 28. 2 . 000 . 001


Canyon Camp, Mont., lot 1311 Continued


Bed

G-9.

Description

Grandeur Tongue of Park City Formation, upper part Continued

Dolomite: hard, light-brownish-gray (IOYR 6/1), thick-bedded, aphanitic; contains a few lenses and nodules of chert; irregular contact with bed below.

Chert: hard, medium-gray (N 5), thick- bedded.

Dolomite: hard, medium gray (N 6), thick-bedded, aphanitic; irregular contact with bed below.

Chert: hard, brownish-gray (IOYR 4/1), thin-bedded; pinches out along strike; irregular contact with bed below.

Dolomite: hard, light-brownish-gray (IOYR 5/1), very thick bedded, aphanitic; irregular contact with bed below.

Chert: dolomitic, hard, dark-gray (N 4), thin-bedded; irregular contact with bed below.

Dolomite: hard, brownish-gray (iOYR 4/1), thick-bedded, aphanitic.

Dolomite: hard, dark-gray (N 4), thick- bedded, aphanitic; contains chert nodules averaging 30 mm in diam eter.

Siltstone: calcareous, medium-hard, pale-brown (10 YR 5/3), thick-bedded; in fault contact with underlying bed.

Thickness (feet)

Cumulativethickness

(feet)

Uranium

Sample P205Acid


eV U

0. 6 236. 8

. 3 237. 1

1. 3 238. 4

238. 6

1. 7 240. 3

240. 5

2. 4 242. 9

3. 5 246. 4

5. 6 252. 0

West Fork of Madison River, Mont., lot 1318

[Part of Permian rocks measured near West Fork of Madison River, SE % sec. 30. T. 12 S., R. 2 W., Beaverhead County, Mont., on northeast limb of small anticline. Phos' phoria Formation measured and sampled in bulldozer trench; Shedhorn Sandstone measured from natural exposure at northeast end of trench. Beds strike N. 30° W- and dip 30° NE. Measured by C. W. Tandy, J. L. Elliott, and E. R. Cressman and sampled by B. K. Replogle, in August 1949. Analyzed for PtOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Qeol. Survey]


Bed

Us-21.

20.

To-18-

16-

15.

14.



Upper member of Shedhorn Sandstone, top not exposed:

Sandstone: hard, light-gray (N 7), 13. 5 13. 5very thick bedded, fine-grained;contains glauconite. Overlying bedsare covered; thickness to contactwith Dinwoody formation is notknown.

Sandstone: hard, light-gray (N 7), 10. 1 23.6very thick bedded, very fine grained;contains glauconite.

Sandstone: hard, medium-gray (N 6), 1. 9 25. 5very thick bedded, very fine grained.

Tosi Chert Tongue of Phosphoria Forma tion :

Chert: brittle, light-brownish-gray 16. 9 42. 4(IOYR 5/1), thick-bedded.

Chert: brittle, light-brownish-gray 10. 6 53. 0(IOYR 5/1), thick-bedded.

Chert: brittle, brownish-gray (IOYR 19. 0 72. 04/1), thick-bedded; contains a fewinterbeds of medium-hard yellowish- gray (IOYR 8/1) thin-bedded chert.

Chert: brittle, light-brownish-gray 1. 3 73. 3(IOYR 6/1), thin-bedded; containsmedium-hard weak-yellowish-orange(2.5 Y 8/4) mudstone partings 0.03ft thick, 0.8 ft above base of bed.

Chert: argillaceous, brittle, light- 13.5 86. 8brownish-gray (IOYR 6/1), thin- bedded.

Uranium

SampleAcid


eU U


West Fork of Madison River, Mont., lot 1318 Continued

Bed

Rt-13.

12-

11.

10.




Uranium

Acid Radiometric Chemical PsOs insoluble eV U

13. 0 99. 8

2. 0 101. 8 JLE-3404

. 8 102. 6 3403

3. 1 105. 7 3402

1. 8 81. 3 0. 003

.8 82. 0 . 003

3. 3 74. 0 . 004

3401

3400

. 9 106. 6

. 5 107. 1

, 3 107. 4

4. 1 111. 5

. 7 112. 2

. 4 112. 6

.8 113. 4 CWT-3397

. 8 114. 2

1. 0 115. 2

17. 8 42. 6 .007

28. 4 20. 0 . 010

0. 002

.001

. 002

. 008

. 012

Description

Retort Phosphatic Shale Tongue of the Phosphoria Formation:

Mudstone: medium-hard, thin-bedded, yellowish-gray grades from (10 KK 7/1) at base to (IOYR 8/1) at top.

Mudstone: brittle, light-brownish- gray (WYR 6/1), thin-bedded.

Mudstone: medium-hard, pale-brown (WYR 5/2), thin-bedded.

Mudstone: brittle, pale-brown (7.SYR 6/2), thin-bedded; grades from bed below.

Phosphorite: muddy, brittle, medium- gray (N 6), thin-bedded, medium- pelletal.

Phosphorite: brittle, medium-gray (AT 6), thick-bedded, medium-pelletal.

Phosphorite: muddy, plastic, pale- brown (WYR 5/3), thick-bedded, medium-pelletal; grades from bed below.

Mudstone: brittle, pale-brown (WYR 5/2).

Phosphorite: brittle, light-brownish- gray (WYR 6/1), thick-bedded, finely pelletal.

Mudstone: phosphatic, plastic, pale- brown (WYR 5/2), thick-bedded; apatite is finely pelletal.

Mudstone: phosphatic, brittle, light- brown (7.5YR 5/6), thick-bedded; apatite is medium pelletal.

Phosphorite: crumbly, dark-gray (AT 3), thick-bedded, coarsely pelletal.

Mudstone: soft, phosphatic, yehowish- gray (10F.R 7/1) to dark-yellowish- orange (WYR 6/8); apatite is coarsely pelletal. Underlying beds are cov ered; approximate position of Meade Peak Phosphatic Shale Tongue of Phosphoria Formation marked by phosphorite float, 45 ft stratigraphically below bed Rt-1.

Lazyman Hill, Mont., lot 1319

[Permian rocks measured on Lazyman Hill, sec. 9, T. 10 S., R. 2 W., Madison County, Mont., on east limb of Ruby Valley syncline. Beds Rt-58 through To-74 exposed in hand trench on east face of hill; beds To-75 through Us-103 measured from natural exposure on east face of hill; rest of section measured from natural exposures on northeast face of hill. Beds strike N. 10° E. and dip 13° W. Measured by E. R. Cressman, B. K. Replogle, and W. J. Qarmoe and sampled by R. F. Qosman, in September 1949. Analyzed for P2Os and acid insoluble by U.S. Bur. of Mines and for other constituents by U.S. Qeol. Survey]


3399

3398b

3398a

-3397

3396

3395

5. 5

29.3

8. 5

12. 5

30. 7

11. 5

63. 3

14. 7

49. 9

49. 3

9.3

55. 0

. 005

. 010

. 006

.007

. 008

. 005

. 004

. 014

. 007

. 006

. 009

. 004

Bed

(104).

To-103.

102.

101.

Description

Beds overlying To-103 are covered; thickness to contact with Dinwoody estimated.

Tosi Chert Tongue of Phosphoria Formation:Dolomite: sandy, medium-hard, very

pale orange (7.5 YR 8/2), thin-bedded'; sand is very fine; contains glauconite and as much as 20 percent dolomitic shell fragments.

Dolomite: medium-hard, very pale brown (WYR 7/3), thin-bedded, aphanitic; contains glauconite.

Sandstone: dolomitic, hard, yellowish- gray (WYR 8/1), thick-bedded, very fine grained; contains glauconite.


(feet) (feet)

10.0 _.___ .

Uranium

Sample P»05Acid Organic Radiometric Chemical

insoluble matter eU U

1. 0 1. 0

1. 5

2. 1


Laeyman Hill, Mont., lot 1319 ContinuedChemical analyses (percent)

Uranium Cumulative

Thickness thickness Acid Organic Radiometric Chemical Bed Description (feet) (feet) Sample PzOs insoluble matter eU TJ

Tosi Chert Tongue of Phosphoria For mation Continued

To-100________ Siltstone: dolomitic, medium-hard, 3.3 5.4 __________ _.__ ____ ____ ______ _______light-gray (N8), thin-bedded; centerone-quarter to one-half of nearlyevery bed consists of cherty hardmedium-gray (N 6) siltstone; con tains glauconite; bedding surfaces areirregular.

99_________ Siltstone: dolomitic, medium-hard, 3. 8 9. 2 __________ ____ ____ ____ ______ _______ pale-orange (7.5YR 8/4), thin-bedded,cross-bedded; contains lenses of crossbedded cherty siltstone averaging0.05 ft by 0.2 ft that comprises 25percent of rock; contains glauconite;bedding surfaces are irregular.

98_-__--_-_ Dolomite: silty, medium-hard, weak- 1. 0 10. 2 __________ ____ _-__ -___ _-___- _______yellowish-orange (1QYR 8/4), fissile,aphanitic.

97_________ Siltstone: dolomitic, medium-hard, .8 11. 0 __________ ____ ____ ____ ______ ___----weak-yellowish-orange (WYR 8/4),thin-bedded.

96_________ Dolomite: silty, medium-hard, weak- 2.4 13.4 __________ _.__ _-__ -__- _--_-_ _______yellowish-orange (WYR 8/4), fissile,aphanitic.

95__.______ Mudstone: dolomitic, medium-hard, .9 14. 3 __________ ____ -___ __-- ------ ___-__.weak-yellowish-orange (WYR 8/4),thin-bedded.

94_________ Dolomite: silty, medium-hard, weak- 2. 3 16. 6 __________ ____ ____ -___ ______ _______yellowish-orange (WYR 8/4), fissile,aphanitic.

(93)______. Covered._________.______________-_ 5.3 21.9 __________ ____ __._ -___ ------ -------Upper member of Shedhorn Sandstone:

Us-92_-__--___ Sandstone: glauconitic, medium-hard, 1.0 22. 9 __________ ____ -___ ---- ------ _______light-gray (N 8) to green, very thickbedded, very fine grained; containsphosphorite pebbles and phosphaticfossil fragments; glauconite occursas matrix.

91_______._ Chert: hard, light-gray (N 8), thin- .4 23.3 ___-.___-_ ____ ____ ---- ------ -------bedded; irregular contact with bedbelow.

90.___-_-__ Sandstone: glauconitic, medium-hard, 2. 3 25. 6 __________ ____ ____ _-__ ------ -------light-gray (N 8) to green, very thickbedded, fine-grained; contains sev eral thin irregular chert laminae.

(89)_______ Covered_______________________ 2.9 28.5 ________ .___ _.._ ---- ------ -------88_________ Sandstone: medium-hard, light-gray 4.1 32.6 __________ _-__ __-- ---- ------ -------

(N 8), thick-bedded, fine-grained;grades from bed below.

87--_-_-.-_ Sandstone: hard, light-gray (N 8), 8.5 41.1 __________ -___ _-__ ---- ------ -------very thick bedded, fine-grained;grades from bed below.

86_ __--_-__ Sandstone: medium-hard, light-gray 4.3 45.4 __________ _-__ ____ __-_ ------ -_-___.(N 8), very thick bedded, fine grained; contains irregular bodiesof fine-grained cherty sandstone0.5 to 2.0 ft in diameter that con stitute 10 percent of rock; gradesfrom bed below.

85_________ Sandstone: hard,.yellowish-gray (WYR 15.2 60.6 __________ ____ __-_ ---- ------ -------8/1), very thick bedded, very finegrained; contains sandy chert masses0.1 to 0.2 ft in daimeter and 0.7 to1.0 ft long that constitute 20 percentof rock; one-third of chert bodies areelongated perpendicular to bedding;grades from bed below.


Lazyman Hill, Mont., lot 1319 ContinuedChemical analyses (percent)

Uranium Cumulative

Thickness thickness Acid Organic Radiometric Chemical Bed Description (feet) (feet) Sample PsOs insoluble matter eV U


Us-84_________ Sandstone: hard,, yellowish-gray (10 YR 8.1 68.7 __________ ____ _.__ ___- ______ .____._8/1), very thick bedded, very finegrained; contains very irregularbodies of sandy chert 0.05 to 1.0 ftin diameter that constitute from 50percent of rock at base of bed to 20percent of rock at top; grades fromchert below.


To-83_-_____._ Chert: sandy, hard, white (N 9), very 9.0 77.7 ...____ _ -___ -_-- ------ --- -thick bedded; sand is very fine; con tains very irregular bodies of veryfine grained sandstone from 0.02 to0.8 ft in diameter constituting sev eral percent of rock at base of unitto 50 percent at top; grades frombed below.

82_________ Chert: exposure is inaccessible.______ 7.9 85.6 __________ ____ ____ ___- ______ ____---81-______-_ Chert: brittle, yellowish-gray (IOYR 8.2 93.8 ________ _.__ ____ ..__ ------

7/1), very thick bedded; irregularcontact with bed below.

80__--_-___ Chert: brittle, light-brownish-gray .6 94.4 __________ .___ ____ ____ ------ _______(10 YR 5/1), thick-bedded; irregularcontact with bed below.

79__.______ Chert: brittle, light-brownish-gray 5.7 100.1 __________ ____ ____ ____ ------ -------(IOYR 5/1), very thick bedded;

78_--_-____ Chert: brittle, lMit-brownish-gray( 10 YR 2.8 102.9 _____-__-_ ____ ____ ____ ------ __. -5/1), thin-bedded; bedding surfacesare undulant; irregular contact withbed below.

77__-_-____ Chert: brittle, light-brownish-gray 8.5 111.4 __________ ____ ___- __-_ ____-- -------(IOYR 5/1), thin-bedded; beddingsurfaces are undulant.

76_--_-_-__ Chert: brittle, light-brownish-gray 3.7 115.1 ---------- ____ __._ ____ ------ -------(IOYR 5/1), thin-bedded; beddingsurfaces are undulant; containsroughly spherical concretions ofmedium-crystalline calcite 1.0 to 2.0ft in diameter; many of the concre tions have weathered out.

75____--__- Chert: brittle, light-brownish-gray 3.2 118.3 ___-_____- ___- ____ __-_ ------ _-_-._-(IOYR 5/1), thin-bedded; beddingsurfaces are undulant.

74__ _______ Chert: brittle, light-brownish-gray 3.5 121.8 ERG-742 0.7 93.8 0.00 0.000 0.000(IOYR 5/1), thin-bedded; beddingsurfaces are undulant.

73_________ Chert: medium-hard, yellowish-white .6 122.4")(IOYR 9/1), fissile.

72_________ Chert: hard, light-brownish-gray .7 123. lV 741 .8 90.4 ____ .002 .001(IOYR 6/1), thin-bedded; gradesfrom bed below. /


Rt-71_________ Mudstone: medium-hard, yellowish- 1.0 124.1 740 . 5 87. 6 .70 .002 .001gray (IOYR 8/1), thin-bedded.

70_________ Mudstone: cherty, hard, yellowish-gray 1.3 125.4 739 1.2 86.3 .79 .001 .002(IOYR 8/1), thin-bedded; gradesfrom bed below.

69_________ Dolomite: medium-hard, light-yellow- .9 126.3 738 1.5 17.0 .85 .002 .003ish-brown (2.5 Y 6/4), thin-bedded;contains a few chert laminae 1 to 2mm thick.

68_________ Phosphorite: cherty, hard, light-gray . 8 127. 1^(JV8), thick-bedded, medium-pelletaland oolitic. > 737 28.0 19.2 .50 .008 .010

67_--______ Phosphorite: crumbly, light-gray (N .4 127.58), thick-bedded, medium-pelletal. )

66___----__ Phosphorite: medium-hard, light-gray .9 128.4 736 33.7 7.6 .59 .008 .011(N 8), thick-bedded, medium-pel letal.



Uranium

0.6

.9

. 1

. 2

. 7

. 1

. 4

. 2

129.0

129. 91

130.0

130.2

130. 9'

131.0

131.4

131.6

6. 1 137. 7 WJG-749


Bed Description (feet) (feef)


Rt-65_________ Mudstone: phosphatic, soft, pale-brown(2.5 Y 5/2); apatite is finely pelletal.

64_ ________ Mudstone: soft, pale-brown (2.5 Y 6/2),fissile.

63__------- Phosphorite: muddy, soft, moderate- reddish-brown, thin-bedded, medium- pelletal.

62_ ________ Mudstone: light olive-brown (2.5 Y 5/6),fissile.

61_________ Mudstone: phosphatic, soft, dark- greenish-gray, thin-bedded; apatite is finely pelletal.

60________ Phosphorite: soft, reddish-brown, thin- bedded, medium-pelletal.

59_________ Mudstone: phosphatic, medium-hard,dark-greenish-gray, thin-bedded.

58 _________ Phosphorite: mediu m-hard, light-brown(7.5YR 5/4), thin-bedded, coarsely oolitic; irregular contact with bed below.

57_______ Chert: hard, light-gray (N 7), thick- bedded; irregular contact with bed below.

56_________ Chert: dolomitic, sandy, hard, pale- 2.0 139.7brown (7. SYR 6/2), thin-bedded; sand is very fine.

Lower member of Shedhorn Sandstone: Ls-55- ________ Sandstone: cherty, hard, very pale 6.1 145.8

brown (10 YR 7/2), thick-bedded, very fine grained; contains chert nodules in lower 0.8 ft.

54. ______ Sandstone: hard, light-gray (N 8), 3.3 149.1thick-bedded, fine-grained; contains a few chert and dolomite pebbles 0.01 to 0.04 ft in diameter.

53_________ Dolomite: hard, pale-orange (7.5YB 1.2 150.38/4), very thick bedded, aphanitic.

52_________ Sandstone: dolomitic, hard, weak-yel- 8.5 158.8lowish-orange (IQYR 7/6), thin- bedded, very fine grained; poorly exposed.

51 _________ Sandstone: brittle, yellowish-gray 6.2 165.0(2.5F 8/2), very thick bedded, fine grained; grades from bed below.

50_________ Sandstone: dolomitic, brittle, yellow- 7.7 172.7ish-gray (2.5F 7/2), very thick bed ded, fine-grained.

49_________ Sandstone: dolomitic, brittle, weak- 2.0 174.7yellowish-orange (IQYR 8/4), very thick bedded, fine-grained.

48_________ Sandstone: hard, medium-gray (N 6), .7 175.4thick-bedded fine-grained; contains phosphatic skeletal fragments; grades from bed below.

47-_--_____ Sandstone: hard, light-brownish-gray .3 175.7 (10 YR 5/1), thick-bedded, fine grained.

46_________ Dolomite: sandy, brittle, pale-brown 2.5 178.2(2.5 Y 5/2), very thick bedded, apha nitic.

45_________ Sandstone: hard, light-brownish-gray 2,0 180. 2(IQYR 5/1), very thick bedded, fine grained.

44_ ________ Dolomite:brittle, yellowish-gray (IQYR 1. 2 181.47/1), thick-bedded, aphanitic.

43 _________ Sandstone: hard, light-gray (N 7), very 2. 3 183. 7fine grained: irregular contact with bed below.


insoluble matter eU U

ERG-735 10.4 49.4 1.47 0.006

734 6. 2 63. 4 1. 51 .005

0.006

.004

733 15. 6 42. 0 . 95

5 93.2

.006

.001

.007

.001



Bed Description


R-42.______. Chert: brittle, yellowish-gray (WYR 7/1), thin-bedded; irregular contact with bed below.

Lower member of Shedhorn Sandstone:Ls-41_ ________ Sandstone: cherty, hard, yellowish-

gray (10 YR 8/1), very thick bedded, fine-grained; irregular contact with bed below.

40_-------- Dolomite: brittle, light-brownish-gray(10 YR 6/1), very thick bedded, aphanitic; contains chert nodules 0.1 to 0.3 ft in diameter, some which have quartzite cores; nodules consti tute 30 percent of bed.

39_._--_ __ Sandstone: hard, very pale brown (10 YR 7/2), very thick bedded, medium-grained; phosphatic fossil fragments.

38__-__-__- Dolomite: brittle, pale-brown (2.5F 6/2), thick-bedded, aphanitic.

37_ ________ Sandstone: hard, light-brownish-gray(10 YR 5/1), thick-bedded, fine grained.

36 _________ Sandstone: phosphatic, hard, light- brownish-gray (WYR 5/1), very thick bedded, fine-grained; contains phosphatic skeletal fragments.

Meade Peak Phosphatic Shale Tongue ofPhosphoria Formation:

M-35 _________ Phosphorite: brittle, light-brownish- gray (10 YR 6/1), thick-bedded, medium-pelletal; contains phosphatic skeletal fragments.

34 ________ Chert: brittle, light-brownish-gray(WYR 5/1), thin-bedded.

33 _________ Mudstone and chert, interbedded:crumbly light-yellowish-brown (10 YR 6/4) thin-bedded mudstone interbedded with brittle dark-gray (N 4) thin-bedded chert.

32 _________ Phosphorite: brittle, yellowish-gray(10 YR 7/1), thin-bedded, coarsely pellet al.

31_________ Phosphorite: brittle, pale-brown (7.5YR 5/2), thin-bedded, coarsely pelletal and oolitic; contains phosphatic skeletal fragments; contains cherty nodules or pebbles K to 1 in. in di ameter near base.

Grandeur Tongue of Park City Formation: G-30-__-_-____ Dolomite: brittle, yellowish-gray (10

YR 7/1), thick-bedded, aphanitic.29_ _________ Dolomite: sandy, brittle, yellowish-

gray (WYR 7/1), very thick bedded, aphanitic.

28__________ Dolomite: brittle, very pale orange(7.5 YR 8/2), aphanitic.

27__________ Dolomite: brittle, yellowish-gray (10 YR7/1), thin-bedded, aphanitic.

26 __________ Dolom ite: bristle, yellowish-gray(10 YR 7/1), thick-bedded.

25__________ Dolomite: brittle, yellowish-gray (2.5Y7/2), thick-bedded, aphanitic.

24__________ Dolomite: brittle, light-gray (N 7),thick-bedded, aphanitic.

23__________ Sandstone: brittle, very pale brown(10 YR 7/3), thick-bedded, fine grained.

22__________ Sandstone: brittle, yellowish-gray(WYR 8/1), thin-bedded, fine grained.

Thick ness (feet)

3 Q

1 3

. 8

1 Q

O

.4

0 C

. 6

4. 2

. 6

. 6

thickness (feet)

187. 6 .

188. 9 .

18Q 7

191. 0 .

m o

191. 6

1Q4. 1

194 7

198. 9

199. 5^

200. 1

Uranium

Acid in- Organic Radiometric Chemical Sample PsO. soluble matter e\J U

BKR-748 0.6 91.0 ____ 0.000 0.001

747 8.5 61.8 _ _ .004 .003

1. 5 201. 6

. 7

6.5

4. 1

4. 1

3. 2

8.6

4.6

5.6

202. 3

208.8

212. 9

217. 0

220. 2

228. 8

233.4

239. 0

746 27. 9 19.3

745 1. 7 20. 3

005 007

001 001

5. 6 244. 6


G-21.

20.

19.

18.

17.

16.

15.

14.

13.

12.

Q-10.

(6).

(4).

(2).

Laxyman Hill, Mont., lot 1319 Continued


Bed Description (feet) (feet) Sample


__--_--.. Carbonate rock: brittle, medium-gray 1.5 246.1 _________(N 6), thick-bedded, aphanitic.

----_-_-. Dolomite: brittle, very pale brown 2. 5 248. 6 _________(1QYR 7/2), thick-bedded, aphanitic;grades from bed below.

__-_____. Carbonate rock: brittle, medium-gray 3.7 252.3 _________(N 6), very thick bedded, aphanitic.

-______._ Dolomite: brittle, light-gray (N 8), 1.8 254.1 _________very thick bedded, aphanitic.

----_--_. Dolomite: brittle, pale-brown (7.SYR 2.9 257.0 _________5/2), very thick bedded, aphanitic.

---______ Dolomite: hard, light-gray (N 7), 3.7 260. 7 _________thick-bedded, aphanitic.

--____-._ Sandstone: hard, pale-orange (7.5 YR 2.6 263.3 _________8/4), very thick bedded, fine-grained.

---__---. Dolomite: hard, pale-brown (10 YR 4.8 268.1 _________6/2), thick-bedded, aphanitic.

---____-. Sandstone: calcareous, hard, weak- 7.0 275.1 _________yellowish-orange (1QYR 8/4), verythick bedded, fine-grained; lower 2.0ft is dolomitic.

_________ Dolomite: hard, weak-yellowish-orange 2. 5 277. 6 _ _______(10 FT. 8/4), thick-bedded, aphanitic.

_________ Dolomite: hard, white (N 9), thin- 3.3 2809 _________bedded, aphanitic.

Quadrant Formation, upper part:--_______ Sandstone, calcareous, hard, white (N 12.0 292.9 _________

9), very thick bedded, fine-grained.---_____. Sandstone: calcareous, hard, dark- 7.0 299.9 _________

yellowish-orange (10 FT. 6/8), verythick bedded, fine-grained.

_________ Sandstone: hard, light-gray (N 8), very 9. 1 209. 0 _________thick bedded, fine-grained; upperpart is calcareous; lower part isdolomitic; grades from bed below.

--_____-_ Dolomite: hard, brownish-gray (10FT. 1.0 310.0 _________3/1), thin-bedded, aphanitic.

- ______ Covered___._______._______ 2.3 312.3 ______._ _____ Sandstone: calcareous, hard, very pale 3.7 316.0 _________

orange (7.5 YR 8/2), thick-beddedfine-grained.

_________ Covered_________________________ 4.5 320.5 ___.____.----_____ Dolomite: hard, yellowish-gray (10Ftf 5.5 326.0 _________

7/1), thick-bedded, aphanitic.- _______ Covered-_--___-___________________ 4.3 330.3 __________________ Sandstone: hard, yellowish-gray (10 YR 7.9 338.2 _______

8/1), very thick bedded, fine-grained.


Uranium

PsOeAcid in- Organic Radiometric Chemical

soluble matter ell U

Little Water Canyon, Mont., lot 1341

A_i<u_r£cu iui .raw auu awu msoiuDie oy u.s. tsur. oi mines ana lor uranium uy u.e. ueoi. survey, unemicai analyses lor i in accord with field descriptions or composition of hand specimens, suggesting that samples taken for analysis were mislabeled]

Bed Description

Tosi Chert Member of Phosphoria Forma tion, lower part:

To-77._______ Chert: hard, medium-gray (_V 5),thick-bedded; contains glauconite.

76________ Mudstone: soft, dark-gray (N 4),thick-bedded.

75__,_.___ Chert: hard, grayish-brown (7.SYR 3/2), thick-bedded; contains glauco nite.

74_ _______ Mudstone: medium-hard, pale-brown(7.5 F.R 5/2), thin-bedded; contains glauconite.


(feet)

Uranium

Sample P_05Acid Radiometric Chemical

eU U

1. 2

. 3

1.0

1. 2

1. 5

2. 5

2.7


Little Water Canyon, Mont., lot 1341 Continued

Bed Description

Tosi Chert Member of Phosphoria Forma tion, lower part Continued

To-73.-..---- Chert: hard, light-gray (AT 8), thick- bedded; contains glauconite; in fault contact with unit below.

Cherty shale member (?) of PhosphoriaFormation:

Cs-72________ Mudstone: hard, dark-gray (N 4),thin-bedded; contains chert lenses; in fault contact with bed below.

Retort Phosphatic Shale Member of Phos phoria Formation; upper part is faulted out:

Rt-71 ________ Mudstone: soft, brownish-black (10 YR2/1), thin-bedded; bed is sheared, and bedding is indistinct.

70________ Similar to bed Rt-71____-_----------69________ Mudstone: soft, dusky-brown (WYR

3/2), thin-bedded.68_-__--__ Mudstone: soft, dusky-brown (WYR

2/2), thick-bedded.67.._---__ Mudstone: soft, dusky-brown (WYR

3/2), thin-bedded; grades from bed below.

66_-_---_- Mudstone: medium-hard, grayish- brown (WYR 4/2), thin-bedded.

65-__-____ Mudstone: soft, dusky-brown (WYR 3/2), thick-bedded.

64________ Phosphorite: medium-hard, brownish- gray (WYR 4/1), thin-bedded, coarsely pelletal and nodular; nod ules are as much as 25 mm in diameter.

63________ Mudstone: soft, dusky-brown (WYR3/2), fissile.

62--_--___ Limestone: medium-hard, pale-brown (2.5 Y 6/2), thin-bedded, aphanitic.

61-_______ Mudstone: soft, brownish-gray (WYR3/1). Fossil-colln. No. 12307.

60_ _______ Phosphorite: medium-hard, dusky- brown (WYR 3/2), thick-bedded, medium-pelletal; contains glauco nite; contains many small gastropod shells replaced by apatite; unit is sheared. Fossil-colln. No. 12307.

59________ Mudstone: phosphatic, soft, brown ish-gray (WYR 3/1), thick-bedded, finely pellatal and nodular; nodules are as much as 12 mm in diameter. Fossil-colln. No. 12307.

58________ Mudstone: phosphatic, soft, brownish- gray (WYR 3/1), thin-bedded; apatite is finely pellatal; grades from bed below. Fossil-colln. No. 12307.

57 ________ Mudstone: medium-hard, dusky- brown (WYR 3/2), thin-bedded; contains a few apatite nodules as much as 4 mm in diameter. Fossil- colln. No. 12307.

56________ Mudstone: phosphatic, medium-hard,brownish-gray (WYR 3/1), thin- bedded; apatite is nodular and finely pelletal; nodules are as much as 15 mm in diameter.

55________ Mudstone: soft, dusky-brown (WYR3/2), fissile. Fossil-colln. No. 12306.

54 ________ Phosphorite: soft, brownish-black(WYR 2/1), nodular and finely pelletal; nodules are as much as 20 mm in diameter. Fossil-colln. No. 12306.

53._______ Mudstone: medium-hard, brownish- gray (WYR 4/1),thin-bedded;grades from bed below.



(feet) (feet)

Uranium

4. 7

2. 6

2. 42. 4

. 9

2. 2

1. 2

1. 5

. 8

. 6


insoluble eU TI

7. 4

13. 8 21. 2

23. 8 TMC-5364 4. 1 53. 8 0. 005

26. 228. 6

29. 5

31.7

53635362

5361

5360

4.5 5.5

8.3

6. 1

5359.9 32.

.6 33. 2

1. 1 34. 3 RGW-5358

35. 5

37.0

37.8

38. 4

5357

5356

5355

5354

21. 9

19. 5

31. 5

4. 1

. 3 38. 71

.3 39. 0

. 8 39. 8

1. 4 41. 2

. 2 41. 4^

1. 7 43. 1

1. 6 44. 7

5353

5325

5351

5350

5349

49. 247. 4

51.9

51. 7

.006

.005

.005

.005

0.003

. 004

.004

. 004

. 004

6. 1 52. 4 . 004

10. 4 39. 7 . 004

24.0

29.9

5.0

53.8

.005

.001

.004

.005

.004

.004

4. 5 49. 2 . 003

5. 5 47. 4 . 004

13. 3 40. 3 . 003

22. 7 19. 9 . 004

3. 8 68. 5 . 004



Bed

Rt-52

50-

49 _

48_

47_

46-

45 _

44.

F-43_.

42.

41.

(40). 39_ _

38.

37-

(36).

Description

Retort Phosphatic Shale Member of Phos- phoria Formation; upper part is faulted out Continued

Mudstone: phosphatic, soft, brownish- black (WYR 2/1); apatite is nodular and finely pelletal; nodules are as much as 25 mm in diameter; grades from bed below.

Phosphorite: muddy, soft, brownish- black (10 YR 2/1), nodular and finely pelletal; nodules are as much as 30 mm in diameter and are more nu merous in lower 0.5 ft of bed.

Mudstone: soft, moderate-yellowish- brown (10 YR 4/4); contains a few apatite nodules as much as 12 mm in diameter. Fossil-colln. No. 12305.

Mudstone: phosphatic, medium-hard, grayish-brown (IOYR 4/2), thin- bedded; apatite is finely pelletal. Fossil-colln. No. 12305.

Mudstone: phosphatic, soft, grayish- brown (10 YR 4/2); apatite is finely pelletal.

Mudstone: phosphatic, soft, moderate- yellowish-brown (10 YR 4/4); apatite is medium pelletal.

Mudstone: phosphatic, soft, brownish- gray (IOYR 3/1); apatite is nodular and finely pelletal; nodules aie as much as 20 mm in diameter.

Mudstone: soft, dusky-brown (10YR 3/2); contains a few apatite nodules as much as 15 mm in diameter.

Mudstone: phosphatic, soft, grayish- grown (7.5 YR 3/2); apatite is nodu lar and finely pelletal; nodules are as much as 4 mm in diameter.

Fj/anson Tongue of Park City Formation: Sandstone: phosphatic, hard, medium-

gray (N 5), very fine grained; con tains apatite nodules as much as 20 mm in diameter and phosphatic skeletal fragments; contains glauconite; grades from bed below. Fossil-collr. No. 12304.

Sandstone: hard, light-yellowish-brown (10 YR 6/4), thick-bedded, fine-grained; contains glauconite and a few apatite nodules and skeletal fragments;

rades from bed below. Fossil-colln. To. 12304.

Limestone: hard, medium-gray (N 5), very thick bedded, fine-grained. Fossil-colln. No. 12303.

Covered,_______-___---_-________-_Sandstone: calcareous, hard, pale-

brown (2.5 Y 6/2), thick-bedded, very fine grained: contains bryozoan frag ments; grades from bed below.

Limestone: hard, pale-brown (2.5F 6/2), thick-bedded: contains chert nodules; grades from bed below. Fossil-colln. No. 12302

Dolomite: silty, hard, pale-brown (2.5 Y 6/2), thick-bedded, aphanitic, con tains chert nodules and columnar bodies of chert 0.1 ft in diameter and 0.4 ft long.

Covered-.._____-_-___-_-__--__---_

grgNo



(feet) (feet)

Uranium

2.9

21.0 3. 5

10.0

Sample PjOtAcid


eU U

1. 5 46. 2 RFG-5348 13.9 41. 3 0. 005 0. 003

1. 8 48. 0

1.8

1.3

48.31

49. 2

49.

50. 1

5347 21. 1 24. 6 006 .004

53. 2

54. 1

56.0

5346

RGW-5345

5344

5343

5342

5341

10. 2 52. 6 .005

10. 4 51. 8

13. 5

5.2

9. 2

11. 1

41.0

56. 1

55. 5

58. 2

56. 9

59.8

80.884. 3

94. 3

5340 6.4 64. 1

.004

.004

.002

.003

.005

.003

.002

.002

.004

10. 0 104. 3

10. 0 114. 3


Little Water Canyon, Mont., lot 1341 ContinuedChemical analyses (percent)

Bed Description


F-35-________ Sandstone: calcareous, hard, very palebrown (10 YR 7/2), very thick bedded fine-grained; contains glauconite in uppermost 3.0 ft; grades from bed below. Fossil-colln. No. 12301.

34__.______ Dolomite: hard, very pale orange (10-YR 8/2), very thick bedded, aphanitic; grades from bed below.

33_________ Sandstone: calcareous, medium-hard,very pale orange (IOYR 8/2), very thick bedded, fine-grained; contains some glauconite in lower part of unit; bed is poorly exposed.


R-32_________ Chert: hard, very pale brown (WYR7/2), thick-bedded; contains glau conite; bed is poorly exposed; grades from bed below. Fossil-colln. No. 12030.

31_________ Phosphorite: sandy, medium-hard,weak-yellowish-orange (2.5 YR 8/4), thin-bedded, nodular and coarsely pelletal; nodules are as much as 10 mm in diameter; contains glauconite and phosphatic skeletal fragments.

30_________ Chert: hard, light-brownish-gray (10-YR 5/1), thick-bedded.

29___ ______ Dolomite: hard, pale-brown (IOYR6/2), thick-bedded, aphanitic.

28_________ Chert: hard, light-brownish-gray (10-YR 5/1), thick-bedded; grades from bed below.

27_________ Chert: hard, medium-gray (N 5), thick- bedded.

26_________ Chert: hard light-brownish-gray (10 YR6/1) thick-bedded chert interbedded with medium-hard light-brownish- gray (7.5 YR 5/4) thick-bedded chert.

25---______ Chert: muddy, very hard, pale-brown(IOYR 6/3), thick-bedded.

24_________ Mudstone: cherty, hard, light-brown ish-gray (IOYR 6/1), thin-bedded.

23_________ Chert: hard, light-brownish-gray (10YR 6/1), thick-bedded.

22_______ Chert: muddy, hard, pale-brown (10 YR5/2), thick-bedded. Fossil-colln. No 12299.

21_________ Mudstone: cherty, medium-hard yel lowish-gray (2.5 Y 7/2), thin-bedded.

20_________ Chert: hard, pale-brown (IOYR 6/2),thin-bedded.

19_________ Mudstone: cherty, soft, light-brownish- gray (IOYR 5/1), thin-bedded.

18__.______ Chert: muddy, hard, light-brownish- gray (IOYR 5/1), thick-bedded.

17_________ Mudstone: cherty, soft, light-brownish- gray (IOYR 5/1)


M-16_ _______ Dolomite: muddy, medium-hard, verypale brown (19YR 7/2), thick-bedded, aphanitic.

15________ Dolomite: muddy, medium-hard, verypale brown (IOYR 7/2), thick-bedded aphanitic.

14________ Phosphorite: soft, grayish-brown (10YR 4/2), thin-bedded, coarsely pel letal.

13________ Mudstone: phosphatic, soft, light-yel lowish-brown (IOYR 6/4).

12__ ______ Phosphorite: soft, pale-brown (IOYR5/3), medium-pelletal.

UraniumCumulative

Thickness thickness (feet) (feet) Sample

Acid Radiometric Chemical insoluble eV U

14. 2 128. 5

2. 8 131. 3

24. 8 156. 1

20. 0 176. 1

. 3 176. 6

. 6 177. 2

1. 6 178. 8

9. 1 187. 9

5. 1 193. 0

3. 4 196. 4

1. 6 198. 0

. 4 198. 4

3. 8 202. 2

. 8 203. 0

1. 4 204. 4

. 6 205. 0

. 6 205. 6

2. 3 207. 9

1. 0 208. 9

1. 5 210. 4

210.

2. 0 212. 5

. 8 213. 3

2 176. 3 TMC-5373 18. 2 45. 6 0.009 0.008

RGW-5372 14. 2

5371 24. 2

43.0 007

Oil

005

Oil

523


Chemical analyse? (percent)

Uranium

Bed

M-ll.

G-L

Description

Meade Peak Phosphatic Shale Member of Phosphoria Formation Continued

Mudstone: dolomitic, soft, pale-brown (IOYR 5f2).

Mudstone: phosphatic, soft, pale-brown (10 YR 5/2); apatite is medium pelletal; grades from bed below.

Dolomite: medium-hard, light-yellow ish-brown (IOYR 6/4), thick-bedded, aphanitic; grades from bed below.

Mudstone: phosphatic, soft, pale-brown (2.5 Y 5/2).

Phosphorite: medium-hard, light- brownish-gray (10 YR 5/1), thick- bedded, very coarsely pelletal.

Mudstone: phosphatic, soft, yellowish- gray (1QYR 7/1), thick-bedded; very coarsely pelletal; grades from bed below.

Phosphorite: soft, light-brownish-gray (10 YR 5/1), thick-bedded.

Mudstone: soft, weak-vellowish-orange (10 YR 7/6), thick-bedded

Phosphorite: soft, light-brownish-gray (10 YR 5/1), thick-bedded; very coarse ly pelletal and nodular; nodules are as much as 6 mm in diameter.

Phosphorite: medium-hard, yellowish- gray (10 YR 7/1), very thick-bedded; coarsely pelletal and oolitic; contains nodules as much as 8 mm in diameter; contains phosphatic skeletal frag ments. Fossil-colln. No. 12298.

Grandeur Member of Park City Formation, uppermost bed:

Dolomite: hard, very pale brown (IOYR 7/3), very thick bedded, aphanitic; underlying beds are covered. Fossil- colln. No. 12297.



0. 6 213.

1.1 215.0V RGW-5370 17.0

2. 6 217. 6

2. 3 219. 9

. 4 220. 3^

. 4 220. 7

.3 221. 51

. 5 221. 8

. 3 223. 3

1. 5 223. 3

5369 7.0

5368 12. 7

5367 20. 2

Acid Radiometric Chemical insoluble eU U

28. 2 0. 010 0. 010

17. 3 .005 . 004

40. 2 .006 . 006

22. 2 .008 . 009

5366 19. 5 29. 9 . 008 . 007

5365 31.5 5.0 .011 .011

5. 6 228. 9

Taylor Creek Ridge, Idaho, lots 1342 and

[LOI, loss on ignition]

Lot 1342[Lower part of Meade Peak Phosphatic Shale Member of Phosphoria Formation measured and sampled from wall of landslide crevasse in NE}4 sec. 19, T. 14 N., R. 41 E.,

Clark County, Idaho, by R. F. Gosman in September 1950. Beds strike N. 80° W. and dip 11° S. Analyzed for PjO 6 and acid insoluble by U.S. Bur. of Mines and for other constituents by U.S. Geol. Survey]


Uranium

Bed

M-5

4

G-2_

Description

Meade Peak Phosphatic Shale mem ber of Phosphoria Formation:

Phosphorite: medium-hard, lam inated to massive, oolitic; contains nodular chert.

Phosphorite: carbonatic, hard, coarsely oolitic to coarsely pisolitic; contains chert nod ules; basal contact undulatory.

Phosphorite: medium-hard, thin- to thick-bedded, coarsely oolitic; contains 0.1 ft lami nated phosphatic shale layer near base and disseminated quartz sand.

Grandeur Tongue of Park City For mation:

Sandstone: medium-hard, mas sive, coarse-grained; contains coarse phosphorite oolites; grades from chert below.

Chert: not measured ---- _--_

Thick- ness (feet)

Cumula- tive thick-

ness (feet) SampleAcid

Insoluble AljOs Fe 2O 3 LOI

Radio-metric

eVChemical

U

3. 5 3. 5 RFG-5562 30. 2 11. 4 0. 68 0. 77 5. 39 0. 013 0. 015

75 4 25 5563 17. 0 13. 6 . 62 1. 35 1. 97

1. 5 5. 75 5564 31.3 12.6 73 83 3.31

006

010

005

011

1. 6 7.35 5565 4.5 85.5 002


Taylor Creek Ridge, Idaho, lots 134% and 1342-A Continued[Section at same locality as lot 1342 but including some overlying strata. Measured by F. S. Honkala and R. W. Swanson, in September 1952 and August 1953]


Bed Description

Ls-28.

F-27.

26.

Lower tongue of Shedhorn Sand stone; uppermost beds not meas ured:

Sandstone: hard, thin-bedded, medium-grained, very pale brown; dolomitic at base; grades from bed below.

Franson Tongue of Park City For mation:

Dolomite: silty, hard, thin- bedded, very pale brown.

Dolomite: hard, thick-bedded to massive; grades from bed be low.

Lower tongue of Shedhorn Sand stone; contains tongue of Rex Chert Member of Phosphoria For mation near base:

Sandstone: hard, massive, me dium-grained, light-gray; cherty at base and contains some chert pebbles; carbonatic at top; irregular basal contact.

Chert: hard, poorly bedded, white to light-gray; top and bottom locally contains chert pebbles; irregular basal con tact.

Sandstone and chert: hard, poorly banded; irregular basal contact.

Sandstone and carbonate rock: 0.3 ft carbonate rock, con taining irregularly distributed chert nodules and fragments from bed below and sandstone stringers, that grades upward to 0.6 ft hard medium-grained sandstone.

Chert: hard, irregularly banded,white to light-gray.

Sandstone: hard, medium-dark- gray ; very irregular basal con tact.

Carbonate rock: contains chert pebbles for nodules and irreg ularly distributed patches of sand.

Chert: hard and poorly banded in lower third; grades upward into concentrically banded nodules and irregularly dis tributed sandy carbonate rock; contains some patches of sand near top.

Ls-17_____ Sandstone: hard, massive medi um-grained, medium-dark- gray; contains chert fragments near top.

Ls-25-

24 _

23_

22.

21.

20.

19.

R-18..

Uranium

Thick- Cumula-ness tive thick-(feet) ness (feet) Sample

Lot 1342-A

PjOsAcid

Insoluble AljOa FejOa LOI

Radio- metric

eUChemi

cal U

1. 1

1. 8

1. 4

1. 5

1. 6

1. 1

2.9

4.3

6. 2

6. 4

7. 3

7. 7

9. 7

2. 9 12. 6

1. 4 14. 0


Taylor Creek Ridge, Idaho, lots 1342 and 134%-A Continued


525

Uranium

Bed

M-16

15

13-

12.

11.

10.

5.

4_

3.

2.

G-l.

Description

Meade Peak Member of Phosphoria Formation:

Siltstone: carbonatic, hard, thin- bedded, light-brownish-gray; contains laminae and thin beds of chert.

Phosphorite: hard, medium- and very coarsely pelletal to oolitic, yellowish-gray (25 Y 7/2); contains much brown apatite matrix; variably sandy upward; locally, contains quartzite pebbles.

Phosphorite: like bed M-15, but less sandy.

Siltstone and phosphorite: medi um-hard thin-bedded very pale brown siltstone contain ing 0.1 ft pelletal phosphorite just about middle.

Limestone: hard, thick-bedded, aphanitic, light-yellowish- brown; contains considerable amounts of medium-grained quartz silt.

Mudstone: medium-hard, thin- bedded; contains thin silt and chert lenses.

Chert: hard, poorly bedded, grayish-white; contains white- weathering apatite pellets.

Siltstone: fissile and shaly at top, thin-bedded in lower part.

Phosphorite and chert: 0.2 ft hard phosphatic chert under lain by 0.3 ft sandy phos phorite; apatite chiefly med ium to coarsely pelletal; quartz grains are fine.

Phosphorite and chert: hard massive medium-light-gray cherty phosphorite and phos phatic chert; irregularly dis tributed and locally quite var iable ; contains considerable amounts of fine quartz sand; irregular basal contact.

Phosphorite: medium-hard, thick-bedded, coarsely oolitic to pelletal, light-gray (N 7); contains 3-in. hard aphanitic limestone lens.

Mudstone: medium-hard, fissile to thin-bedded.

Phosphorite: hard, massive, coarsely oolitic, medium-light- gray; contains abundant shell fragments; soft at base.

Phosphorite: soft, coarsely oolitic, light-olive-gray (5 Y 6/1).

Phosphorite: sandy, medium to coarsely oolitic, pale-brown (WYR 5/2); contains abun dant shell fragments.

Grandeur Tongue of Park City For mation, top bed:

Sandstone: calcareous, hard, massive, fine-grained, yellow ish-gray (1QYR 7/1).

Thick- Cumula-ness five thick-(feef) ness (feet)

1. 0 15. 0

.7 15. 7

.6 16. 3

.2 16. 5

1. 0 17. 5

1. 1

1.5

18. 6

19. 2

20. 7

21. 2

1. 5 22. 7

1. 0 23. 7

.2 23. 9

1. 8 25. 7

.2 25. 9

.3 26. 2

2. 1 28. 3

SampleAcid

PjOs Insoluble FejOa

Radio- metric Chemi-

LOI <U cal U

709-931 O-64 17


Camp Frigid, Mont., lots 1843 and 1343-A

[LOI, loss on ignition]Chemical analyses (percent)

Uranium

Thick- Cumula- Radio- nest tive thick- Acid metric Chemi-

Bed Description (feet) ness (feet) Sample PjO6 Insoluble A1SO3 Fe.Oj LOI «U cal ITLot 1343

[ Meade Peak Phosphatic Shale Member of Phosphoria formation measured and sampled from natural exposure near top of scarp slope of Centennial Mountains near 81/4 corner sec. 34, T. 14 S., R. 1 W., Beawrbead County, Mont,, by B. K. Beplogle, in September 1950. Beds strike about N. 80° W. and dip 12° S. Analyzed for PjOj and acid insoluble by U.S. Bur. of Mines and for other constituents by U.S. Geol. Survey].

Lower tongue of Shedliorn Sand stone, basal bed:

Ls-8______ Sandstone: hard, massive, yel- 1.0 1.0 BKR-5561 4.7 62.2 ____ ____ 0.002 Ipwish-gray (WYR 8/1); 0.1 ft light-gray limestone at base.

Meade Peak Phosphatic Shale Mem ber of Phosphoria Formation:

M-7______ Phosphorite: hard, pelletal to .75 1.7 5560 32.4 7.0 __ __ ___ .012 0.013nodular, brownish-black (10 YR2/1).

(6).__ Covered..._____________ 9.0 10.7 _________ __ _- ---- - ----- 5______ Phosphorite: hard, massive, 1.8 12.5 5559 33.9 2.8 0.24 0.28 4.30 .016 .018

coarsely oolitic, light-gray (N 7); arbitrary basal contact.

4______ Phosphorite: like bed M-5; 2.2 14.7 5558 33.4 6.3 .83 .38 3.45 .015 .012basal contact somewhat gradational.

3______ Limestone: sandy, hard, mas- 1.8 16.5 5557 3.7 39.7 .10 .43 24.01 .002 sive, yellowish-gray (10F.K 8/1); contains apatite pellets and shell fragments; top 2 in. conglomeratic.

2______ Phosphorite: hard, massive, 2.4 18.9 5556 31.0 9.3 .28 .43 5.68 .007 .009medium coarsely pelletal, medium-gray (N 5); contains small chert pebbles near top and bottom; irregular basal contact.


G-l______ Limestone: hard, massive, very 2.5 21.4 ___________ ____ ____ _-__ --_- ____- _-_-_ -____light gray (AT 8).

Lot 1343-A

[A section across the entire Meade Peak Member about 140 feet west of locality of lot 1343 was measured by F. S. Honkala, in August 1952, and the section between the Meade Peak and Retort Members at this locality was measured in reconnaissance by R. W. Swanson, in August 1956]

Retort Phosphatic Shale Member of Phosphoria Formation, basal bed:

Rt-37_____ Phosphorite: poorly exposed and ____ _____ ___________ _-__ ___- -___ ---- ----- ----- ___--not described.

Lower tongue of Shedhorn Sand stone:

Ls-36___-_ Sandstone: hard, massive, me- 19.5 19.5 ___________ ____ ____ -___ _--- _-__- __--_ _-___dium-grained, light-brown ish-gray; contains many col umnar concretions as much as 5 ft or more long and 0.3 ft diameter, about normal to bedding, speckled with apatite grains and generally cherty; top 1/2 in. phosphatic.

35_____ Sandstone: about 0.2 ft chert 4.4 23.9 ___________ ..__ ____ -___ _--- ----- ----- -----pebble conglomerate at base overlain by sandstone; poorly exposed.

34___._ Sandstone: cherty, hard, light- .6 24.5 ___________ ___- __-- ---- ---- ----- ----- -----brownish-gray; contains con siderable amounts of apatite; no parting at base but sand stone stuck fast like plaster to carbonate rock below.

Franson Tongue of Park City For mation:

F-33_____ Carbonate rock: hard, massive, 1.7 26.7 ___________ -_-_ --_- __-- ---- ----- ----- -----aphanitic, light-gray; locally sandy and contains irregular streaks of sandstone.


Camp Frigid, Mont., lots 1343 and 1343-A Continued


Bed Description

Franson Tongue of Park City For mation C ontinued

F-(32)-_-_ Carbonate rock: sandy, hard, massive, light-gray; contains numerous sandy chert nod ules; top one-half in. is com posed of cherty phosphorite that is stuck fast like plaster to underlying carbonate rock.

(31) _ _ _ _. Covered: mostly carbonate rock float.

30_-_-_- Carbonate rock: sandy, hard, thin-bedded to massive, light- gray.

29_____- Carbonate rock: hard, massive, finely crystalline; locally sandy to silty, iron-stained; shaly parting at top.

28-_-__- Mudstone: soft, thin-bedded-__27--____ Carbonate rock: medium-hard,

thin-bedded to laminated; shaly zone below middle; top 0.7 ft 30 percent fine sand in thin layers.

26______ Mudstone: silty to finely sandy,soft, laminated.

25______ Carbonate rock: silty, hard,massive, aphanitic, very pale brown.

24______ Mudstone: carbonatic, soft, fis sile, light-brownish-gray; con tains 0.15 ft dolomite in lower half.

23___-_- Carbonate rock: sandy, hard, massive, light-gray; grades from bed below.

22-_____ Sandstone: hard, massive, light- gray, speckled; grades from bed below.

21______ Carbonate rock: hard, massive,light-gray, somewhat sandy.

20-_____ Chert and carbonate roek: 60 percent chert grades upward into carbonate rock, pebbly.

19- _____ Chert and mudstone: hard nod ular to wavy-bedded gray chert with matrix of soft mudstone; weathers to form under cut in cliff.

18_-_-_- Carbonate roek: hard, thick- bedded, light-gray, locally gritty to pebbly.

17_---__ Sandstone: phosphatic, calcare ous, hard, thick-bedded me dium-grained; quartz grains angular.

Meade Peak Member of PhosphoriaFormation:

M-16_____ Chert________ _______________15-__-_ Phosphorite: hard, coarsely pel

letal; contains chert.14_____ Siltstone: soft, faintly lami

nated, mottled yellowish- brown and bluish- to greenish- gray; includes 10-in. sandy carbonate rock lens near top.

13 _____ Phosphorite: coaresly oolitic12_ -___ Mudstone-__________________11. - _ _ _ Phosphorite: coarsely oolitic

Thick- Cumula-ness live thick-(feet) ness (feet)

2. 5 28. 7

6. 0 34. 7

4. 1 38. 8

2. 8 41. 6

.3 41. 91. 7 43 6

.3 43. 9

2. 3 46. 2

.8 47. 0

1. 1 48. 1

1. 1 49. 2

1. 1 50. 3

.4 50. 7

.5 51. 2

.9 52. 1

.9 53. 0

.2 53. 2

.7 53. 9

1. 8 55. 7

. 25 55. 95. 7 56. 65. 2 56. 85

Uranium

Sample PsOsAcid

insoluble AhOj LOI


eU cal U


Camp Frigid, Mont., lots 1343 and 1343-A Continued


Uranium

Bed

Thick- Camula- ness tive thick- (feet) ness (feet)

Acid insoluble Fe2 0s


LOI eU cal U

M-10. 9.

Description (feet) ness (feet) Sample

Meade Peak Member of Phosphoria Formation Continued

Mudstone--_---------___-___ 1.8 58.65 ___________ __-_ -___ _-__ ---- ----- ----- -----Phosphorite: soft, coarsely .7 59.35 ___-_---___ -___ ____ ____ --__ _____ _____ _____

oolitic. Mudstone--------___________ .25 59.6 ___-_-__-__ ____ ____ ____ -___ ----- _-___ _____Chert--_-------------___-___ .4 60.0 ____--__-__ ____ ____ ____ -___ ----- ----- -----Mudstone_-_-----______- __ .5 60.5 ___________ ____ ____ ____ ___- _____ _____ _____Phosphorite: soft, thin-bedded, 1.0 61.5 ___________ -___ -___ -___ -___ _____ _____ _____

coarsely oolitic. Phosphorite: medium-hard, mas- 3.4 64.9 ______-__-- ____ ____ ____ -___ _____ _____ _____

sive, coarsely pelletal and oolitic, light-brownish-gray; basal part sandy and rich in shell fragments; basal contact very irregular, having 0.8 ft relief.

Limestone: sandy, hard, mas- 3. 7 68. 6 ___________ ____ ____ ____ ____ _____ _____ _____sive, yellowish-gray; locally gritty; contains chert nod ules and apatite pellets and shell fragments; both contacts irregular and bed ranges in thickness from 3.3 to 4.1 ft.

Phosphorite: sandy, hard, mas- 2.2 70.8 ___________ ___. ____ ____ ____ _____ _____ _____sive, medium coarsely pelletal; contains abundant shell and tooth fragments; contains chert fragments; thickness 2.0 to 2.4 ft; irregular basal con tact.


Limestone: sandy, hard, mas- 4.4 75.2 ___________ ____ ____ ____ -___ _____ _____ _____sive, aphanitic, light-brown ish-gray; top part contains phosphate pellets and shell fragments and much fine grained quartz and probably belongs to Meade Peak inter val although practicable con tact remains at top of interval.

South Big Hole Canyon No. 1, Mont., lot 1354-A[Park City Formation and Eetort Phosphatic Shale Tongue of Phosphoria Formation measured in natural exposure'and hand trench near top of ridge on south Fideof Big

Hole Riverin SEJ4 sec. 3, T. 5 S., R. 8 W., Beaverhead County, Mont., on northwest limb of faulted anticline. Beds strike N. 60° E. and dip 20° N W. Measured by J. A. Peterson and sampled by R. F. Gosman, in June 1951. Analyzed for PzOs and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Oeol. Survey]

G-l.


Bed

Rt-23.

22_

20.

19.

Description

Retort Phosphatic Shale Tongue of Phos phoria Formation, lower part:

Mudstone: phosphatic, medium-hard, black (N 1), thick-bedded; apatite is medium pelletal; grades from bed below.

Phosphorite: muddy, soft, brownish- black (WYR 2/1), medium-pelletal; grades from bed below.

Phosphorite: muddy, soft, dusky-brown (1QYR 3/2), medium-pelletal.

Dolomite: medium-hard, pale-brown (1QYR 6/2), very thick bedded, aphanitic.

Mudstone: phosphatic, soft, grayish- brown (IQYR 4/2); apatite is finely pelletal; grades from bed below.

Thick ness (feet)

1.0

1. 6

3.0

1.0

1.3

Cumulativetfl lCK7lf!33

(feet)

Uranium

Sample P20 5Acid in soluble

Radio- metric eV

Chemical U

1. 0 JAP-5468 12. 6 49. 1 0. 006 0. 002

2.6

5. 6

6.6

7.9

5467

5466

5465

5464

25.4

20. 3

1. 1

16. 2

22. 4

29. 5

4. 1

39. 1

008

008

. 001

. 006

.008

. 007

.006


South Big Hole Canyon No. 1, Mont., lot 1354-A Continued


Bed Description

Retort Phosphatic Shale Tongue of Phos-phoria Formation, lower part Con.

Rt-18_________ Dolomite: muddy, soft, black (N 1),aphanitic; grades from bed below.

17__--_--_- Mudstone: phosphatic, soft, grayish- brown (1QYR 4/2), finely pelletal; grades from bed below.

16__-______ Phosphorite: soft, variegated gray, red,and brown, finely pelletal.

15-_-_-___- Fault breccia: fragments of phos phorite and carbonate rock in medium-crystalline carbonate ma trix.

14_________ Carbonate rock; phosphatic, soft, varie gated gray, red, and brown, apha nitic; apatite is finely pelletal. Bed is brecciated and recemented.

Franson Member of Park City Formation: F-13-_____-_-_ Limestone: soft, moderate-reddish-

brown (1QYR 4/6), very thick bedded, very coarsely crystalline.

12__________ Dolomite: hard, light-gray (N 7), verythick bedded, aphanitic; grades from bed below.

ll-_-_______ Chert: sandy, hard, very pale brown(10YR 7/2), very thick bedded; grades from bed below.

10______-___ Dolomite: hard, pale-brown (IQYR6/2), very thick bedded, aphanitic; grades from bed below.

9__________ Dolomite: medium-hard, light-brown ish-gray (lOFfi 6/1), very thick bedded, aphanitic; contains chert nodules in uppermost 10 ft.

Rex Chert Tongue of Phosphoria Forma tion (?) :

R-8.--________ Chert: hard, pale-red (5R 6/2), verythick bedded.

(7) _________ Covered___--_----_-___---------__-Grandeur Member of Park City Formation:

G-6_ __ ________ Dolomite and chert, interbedded: hardlight-gray (N 7) very thick bedded aphanitic dolomite interbedded with hard light-gray (N 8) very thick bedded chert.

5_--________ Dolomite and chert, interbedded: hardyellowish-gray (1GYR 7/1) very thick bedded aphanitic dolomite inter bedded with hard light-gray (N 8) very thick bedded chert; dolomite contains a few chert nodules.

4_ __________ Dolomite: hard, light-brownish-gray(IOYR 6/1), very thick bedded, aph anitic; unit is partly covered.

3___________ Limestone: sandy, medium-hard, thick- bedded, pale-red (1GR 6/2), med ium-crystalline; sand is very fine.

2__.________ Limestone: sandy, medium-hard, pale- reddish-brown (WR 5/4), very thick bedded, medium-crystalline.

!___________ Limestone: medium-hard, reddish- brown (10R 5/4), thick-bedded, medium-crystalline; underlain by very thick bedded sandstone of Quadrant Formation.



1. 4 9. 3 JAP-5463

1.8 11.1 5462

1.8 12.9 _---__----

.4 13.3 __________

Uranium

Acid in soluble

Radio- Chemical metric e~U U

1. 8 15. 1

3. 3 18. 4

7. 5 25. 9

5. 0 30. 9

20. 3 51. 2

29. 0 80. 2

6. 6 86. 8

12. 5 99. 3

19. 0 118. 3

39. 4 157. 7

14. 0 171. 7

6. 7 178. 4

5. 2 183. 6

4. 8 188. 4

1. 8

17.3

40. 2 0. 005

42. 5 . 006

0. 004

.006


R-12_

M-ll.

10.

South Big Hole Canyon No. 2, Mont., lot 1354-B

[Meade Peak Shale Tongue of Phosphoria Formation measured in hand trench on ridge about 1 mile south of Big Hole River in SE//sec. 9, T. 5 S., R. 8 W., Beaverhead County, Mont. Measured by J. A. Peterson and sampled by R. F. Qosman, in June 1951. Analyzed for uranium by U.S. Qeol. Survey and for other constituents by U.S. Bur. of Mines. LOI, loss on ignition]


Bed Description

Rex Chert Tongue of Phosphoria Formation:

Chert: very thick bedde Meade Peak Phosphatic

Tongue of Phosphoria Formation: Mudstone: medium-hard, pale-

brown (7.5 YR 6/2), bedded; grades from below.

Mudstone: medium-hard, gray ish-red (5R 4/2), thin-bedded.

9 ______ Phosphorite: medium-hard, yel lowish-gray (IOYR 7/1), thin- bedded, medium-pelletal.

8---___ Mudstone: medium-hard, gray ish-red (5fl 4/2), thin-bedded.

7 ______ Phosphorite: medium -brownish-gray (10Y.R bedded, coarsely pelletal.

6 _ _ _ _ _ _ Phosphorite: me(medium-gray (N 6), thick- bedded, coarsely pelletal.

5 ------ Phosphorite: medium-hard, light- gray (N 8), thii coarsely pelletal and oolitic.

4_-___- Phosphorite: sandy, hard, light-bro^ (10Y7. 6/1), thii medium-pelletal; sand is medi um; contains apatite nodules as much as 50 mm in diam eter; contains phos skeletal fragments.

'Grandeur Member of ParkFormation:

G-3__.--__ Mudstone: sandy, dolemedium-hard, variegated ma roon, gray, and yellow; grades from bed below.

2____-_- Mudstone: sandy,medium-hard, lig ish-brown (WYR 6/4)", thin- bedded.

!_____.- Dolomite and chertbedded.

phoria

Shale lation :

pale-thin-

i bed

gray- edded. d, yel-

d. gray-

edded. hard, 3/D,

il. i-hard, thick-

tl. l.light- edded, litic. 3dium- h-gray edded, 3 medi- odules diam- phatic

City

3d ma- grades

rellow- thin-

inter-

Thick- ness (feet)

6.0

2. 7

. 5

. 2

. 7

.3

.5

1. 0

.5

1. 2

5. 2

17. 3

Cumu-

thickness (feet)

6. 0

8. 7

9. 2'

9. 4

10. 1

10. 4

10. 9

11. 9

12. 4

13. 6

18.8

36. 1

Uranium

Acid Radio- Chem- in- metric ical

Sample PjO5 soluble A1SO3 FejO3 LOI eU U

JAP-5399 1.7 79.7 __._ ____ ____ 0.002 _____

5398 6.7 68.0 ____ ____ ____ .003 _____

5397 33. 0 10. 7 3. 89 0. 68 2. 67 . 009 0. 010

5396 34. 4 7. 3 1. 80 1. 99 2. 61 . Oil . 010

5395 37. 6 2. 8 1. 16 . 64 2. 74 . 009 . 009

5394 20. 5 39. 2 1. 19 2. 54 2. 25 . 006 . 006

3593 .4 69.9 ____ __.. _._. .001 _____

5392 .2 69.9 ____ ___. ____ .001 _____


Jefferson Canyon, Mont., lot 1355[Permian rocks measured in natural exposure and hand trench about 200 feet above river on west side of Jefferson Canyon, SE}4 sec. 13, T. 1 N., R. 3 W., Madison County,

Mont. Beds strike N. 45° E. and dip 45° N W. Measured by J. A. Peterson and sampled by R. F. Gosman, in June 1951. Analyzed for PsOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

E-36.

Us-35.

34.

33 _

To-32.

31.

30.

29.

Us-28.

27.

26.

25.

24.

To-23.

22.

21.

20.

19.

18.

Description

Ellis Group basal bed:Sandstone: pebbly; contains oyster

shells; irregular contact with bed below.

Upper tongue of Shedhorn Sandstone; con tains tongue of Tosi Chert Member of Phosphoria Formation:

Chert: hard, pale-brown (2.5F 6/2), thin-bedded.

Sandstone: hard, yellowish-gray (10 YR 7/1), thick-bedded, very fine grained; contains scattered elongate yellowish- white (10FR 9/1) chert nodules at base; composition grades upward to about 60 percent chert nodules, beds, and stringers near center of unit to all sandstone in uppermost 2 ft.

Sandstone and chert interbedded: hard light-brownish-gray (10 YR 6/1) thin- bedded fine-grained cherty sandstone interbedded with hard light-brownish- gray (10 YR 6/1) chert.

Chert: hard, pale-brown (10 YR 5/3), thin-bedded.

Chert: hard, light-brownish-gray (10 FR 5/1), thin-bedded.

Chert: sandy, hard, light-brownish- gray (10 YR 5/1), thick-bedded; sand is fine; grades from bed below.

Chert: hard, light-brownish-gray (IOYR 5/1), thick-bedded.

Sandstone: hard, light-gray (N 7), thick-bedded, fine-grained; upper half of unit contairs phosphatic skeletal fragments and scattered phosphorite nodules as much as 25 mm in diameter.

Chert: hard, light-brownish-gray (IQYR 6/1), thin-bedded.

Sandstone: hard, yellowish-gray (10 FR 7/1), very thick bedded, fine-grained.

Sandstone: hard, light-gray (N 7), very thick bedded, fine-grained.

Sandstone and chert, interbedded: hard light-gray (N 7) thick-bedded fine-grained sandstone interbedded with hard light-brownish-gray (10F.R 5/1) thin-bedded chert.


Chert: phosphatic, medium-hard, me dium-gray (N 5), thick-bedded; con tains apatite nodules that average 8 mm and are as much as 20 mm in diameter; slightly irregular contact with bed below.

Chert: hard, light-brownish-gray (IQYR 5/1), thick-bedded.

Phosphorite: cherty, hard, light- brownish-gray (10F.R 5/1), contains a few apatite nodules as much as 30 mm in diameter; thick-bedded, skel etal and coarsely pelletal; slightly irregular contact with bed below.

Chert: hard, pale-brown (IQYR 5/3), thin-bedded.

Chert: phosphatic, medium-hard, light-brownish-gray (IQYR 5/1), thick-bedded; apatite is skeletal and finely colitic and pelletal.

Chert: hard, black (N 1), thin-bedded_


5.0

1. 5

10. 5

1.9

2.0

3.6

SampleAcid in soluble


1.5

12.0

13.9

1. 7 15. 6

7. 8 23. 4

1. 0 24. 4

26. 4

30.0

.5 30. 5

2. 8 33. 3

1. 2 34. 5

5. 9 40. 4

.3 40. 7 JAP-5384 18. 6 48. 4 0. 003

2.9 43.6 _.__._-___

.5 44. 1 5383 18. 2 45. 0 003

1. 8 45. 9

.5 46. 4

.7 47. 1

5382 15. 5 53.6 002


Jefferson Canyon, Mont., lot 1355 Continued


Bed

To-17.

16.

15.

14.

13.

12.

Rt-11.

10.

9_

To-7.

6.

Description


Chert: phosphatic, hard, medium-gray (N 5), thick-bedded; apatite is medium-pelletal and oolitic.

Chert: medium-hard, black (N 1), thick-bedded.

Dolomite: cherty, medium-hard, black (N 1), thick-bedded.

Chert: dolomitic, hard, brownish-gray (IOYR 3/1), thick-bedded.

Chert: phosphatic, medium-hard, dark-gray (N 3), thin-bedded; apa tite is coarsely pelletal; grades from bed below.

Chert: muddy, medium-hard, brown ish-gray (WYR 4/1), thin-bedded.


Phosphorite: cherty, medium-hard, brownish-gray (IOYR 3/1), thick- bedded, coarsely oolitic and pelletal.

Mudstone: cherty, medium-hard, dark- gray (N 3), thick-bedded.

Phosphorite: cherty, medium-hard, pale-brown (IOYR 5/2), very coarsely pelletal and oolitic; contains phos phatic skeletal fragments and a few apatite nodules as much as 45 mm in diameter.

Mudstone: soft, pale-brown (2.5 Y 5/2),fissile.

Tosi Chert Member of Phosphoria formation lower part:

Chert: hard, light-brownish-gray (IOYR 5/1), thick-bedded.

Phosphorite: hard, medium-gray (N 5), thick-bedded, medium-pelletal and oolitic; contains some phosphatic skeletal fragments; grades from bed below. Fossil-colln. No. 12693.

Sandstone: cherty, hard, medium-gray (N 5), thick-bedded, fine-grained; contains phosphatic skeletal frag ments; contains chert and quartzite pebbles in a zone about 0.5 ft above base of bed.

Chert: medium-hard, mottled light- gray, brown, and yellow, thick- bedded.

Lower tongue of Shedhorn Sandstone:Sandstone: medium-hard, light-gray

(N 7), thick-bedded, fine-grained; rounded chert and quartzite pebbles are as much as 20 mm in diameter.

Sandstone and chert, interbedded: medium-hard, yellowish-gray (IOYR 7/1) thick-bedded fine-grained sand stone contains a few interbeds of chert; layer about 0.8 ft thick that contains chert and quartzite pebbles as much as 50 mm in diameter occurs approximately 5 ft above base of unit; grades from bed below.

Sandstone: pebbly, medium-hard yel lowish-gray (IOYR 7/1), thick- bedded, fine-grained; pebbles are composed of quartzite and chert; underlain by interbedded gray dolo mite and chert of the Franson and lower tongues of the Park City For mation.


Uranium

0.6

. 7

1.0

10. 4

. 5

3.6

.9

3.5

6.3

12. 5

1. 0

47. 2 JAP-5381

48.4

49.4

60.3

63.9

68. 3

69.2

69.6

75.9

76. 3

77. 2

77. 7

78.2

90. 7

91. 7

P 205

17. 5

Acid in soluble

Radio- Chemical metric «U U

46. 8 0. 004

5380

5379

5378

5377

5376

5375

64. 3

2. 0 75. 0

22. 1

1. 1

24. 7

1. 7

31.9

64. 0

32. 4

72. 1

.003

. 002

.005

.002

.009

.003

0.006

.009

5374 7.3 77.9 . 003


Three Forks, Mont., lot 1356

[Permian rocks measured in natural exposure at north end of Milligan Canyon about 300 ft east of Willow Creek road, sec. 24, T. 2 N., R. 1 W., Jefferson County, Mont. Beds strike N. 80° E. and dip 25 ° N. Measured by ,T. A. Peterson and sampled by R. F. Gosman, in June 1951. Analyzed for P2 Os and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

US-32.

To-31_

30.

29-28.

27. 26-

25.

24.

23.

22.

20_

19-

18.

17.

16.

15.

14.

13. 12.

11-

10.

LS-9.

Description Upper tongue of Shedhorn Sandstone (?):

Sandstone: overlain by basal con glomerate of Ellis Group.


Mudstone: dolomitic, hard, light- yellowish-brown (WYR 6/4).

Phosphorite: cherty, hard, brownish- gray (WYR 4/1), medium-pelletal; contains a few oolites and phosphatic skeletal fragments.

Chert: hard, brown___--___-____-___Phosphorite: pebbly, sandy, soft,

brownish-gray (WYR 3/1), nodular, medium-pelletal and colitic; sand is fine; pebbles are composed of chert.

Limestone: dark-gray_ ______________Chert: brittle, light-brownish-gray

(WYR 5/1).Phosphorite: cherty, hard, brownish-

gray (WYR 4/1), nodular, finely pelletal; nodules are as much as 30 mm in diameter.

Chert: muddy, hard, pale-brown (2.5 Y 6/2).

Chert: phosphatic, hard, medium-gray (N 5); apatite is finely pelletal; contains phosphatic skeletal frag ments.

Chert: hard, pale-brown (WYR 6/2)__Chert: phosphatic (?), hard grayish-

brown (2.5F 4/2).Chert: hard, light - brownish - gray

(WYR 5/1).Chert: hard, light - brownish - gray

(WYR 5/1).Dolomite: hard, light-brownish-gray

(WYR 5/1), aphanitic.Chert: muddy (?), hard, light-brownish-

gray (WYR 5/1).Chert: phosphatic, hard, brownish-

gray (WYR 3/1); apatite is coarsely pelletal.

Phosphorite: cherty, hard, light-brown ish-gray (WYR 6/1), coarsely oolitic.

Chert: dolomitic, hard, brownish-gray (WYR 3/1).

Chert: brittle, dusky-brown (10YR 3/2)_Chert: phosphatic, hard, brownish-

gray (WYR 3/1); apatite is skeletal, nodular and medium pelletal; nodules are as much as 20 mm in diameter.

Dolomite: cherty, hard, brownish-gray (WYR 3/1), thin-bedded, aphanitic.

Dolomite: cherty, hard, grayish-brown(2.5 Y 4/2), aphanitic.

Lower tongue of Shedhorn Sandstone:Sandstone: cherty, pebbly, hard, light-

brownish-gray (WYR 5/1), fine grained; chert, quartzite, and dolo mite pebbles are as much as 25 mm in diameter.

Franson and Grandeur Members of Park City Formation, undifferentiated:

Dolomite and chert: hard yellowish- gray (10YR 8/1) silty dolomite con taining 25 to 35 percent of hard light- brownish-gray (WYR 6/1) very ir regular chert nodules and lenses.

Thick- Cness . (feet)

1. 0

6. 2

. 2

2. 3 . 1

. 9

.3

. 3

. 7

. 3

7.0 1. 0

1. 5

1. 0

. 5

2. 0

. 5

. 5

2. 5

7.3 1. 6

1. 5

. 6

Uranium

thickness Acid in- Radio- Chemical (feet) Sample FiOs soluble metric eU U

10

7.2 __-____-_. ------ -__-_- ___---

7. 4 JAP-5405 18. 8 44. 7 0. 005

9 79 8

10 711.0 ______-_-_ ______ ______ ______

11. 3 5404 20. 2 44. 7 . 005

12.0 _-_-----_- ------ ------ _-_-_-

12. 3 5403 18. 9 43. 4 . 007

19 3on q

21.8 __--_-_-__ ______ ------ ------

22.8 _-_--__-_. __--_- ______ _'_-_--

23.3 __________ ______ ______ ------

25.3 __________ ------ ------ _-- --

25. 8 5402 10. 9 64. 0 . 003

26. 3 5401 23. 7 35. 7 . 009

28.8 ______-__. ______ ------ ------

36. 1 __________ ------ ------ ------37. 7 5400 16. 3 50. 0 . 005

JQ 0

39. 8 ---------- ------ __-_-- ------

0. 004

. 006

.005

. 008

. 005

26. 3

42. 7

69. 0


Three Forks, Mont., lot 1356 Continued


Bed

Thick ness (feet)

Cumulativethickness

(feet)

Uranium

SampleAcid in- Radio- Chemical soluble metric eV U

PC-7.

6.

4. 3

21. 3

73.3

94.6

7. 0 101. 6

Description

Franson and Grandeur Members of Park City Formation, undifferentiated Con.

Sandstone: hard, very pale brown(IOYR 7/3), very fine grained.

Dolomite and chert: hard yellowish- gray (IOYR 8/1) silty dolomite con taining 25 to 35 percent of hard light- brownish-gray (IOYR 6/1) chert in very irregular nodules and lenses.

5__________ Dolomite: silty, medium-hard, light- brownish-gray (IOYR 6/1), apha nitic; contains numerous chert nod ules and lenses.

4__________ Sandstone: hard, yellowish-gray (10YR 7/1), thin-bedded, fine-grained.

3__________ Dolomite: hard, pale-brown (2.5 Y 6/2)aphanitic.

2__________ Sandstone: hard, pale-brown (2.5F6/2), fine-grained.

!__________ Dolomite: silty, medium-hard, verypale brown (IOYR 7/2), aphanitic; underlain by very thick bedded sand stone of the Quadrant Formation.

Sappington Canyon, Mont., lot 1357

[Permian rocks measured in natural exposure along ridge on east side of Jefferson River in sec. 25, T. 1 N., R. 2 W., Gallatin County, Mont. Beds strike N. 80° W. and dip 41° N. Measured by J. A. Peterson and sampled by R. F. Qosman in July 1951. Analyzed for PjOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


1. 5

2. 3

. 9

1.7

103. 1

105. 4

106. 3

108. 0

Uranium

Bed

E-46._

45_

Us-44.

43.

To-42.

41_

40-

39_

38.

Description

Ellis Group, basal part:Limestone: sandy, medium-hard, yel

lowish-gray (5Y 7/2), thin-bedded; contains many shell fragments and scattered crinoid stem fragments; grades from bed below.

Mudstone: calcareous, soft, thin- bedded.

Upper tongue of Shedhorn Sandstone:Sandstone: hard, light-yellowish-brown

(WYR 6/4), thick-bedded, medium- grained; contains chert and quartzite pebbles as much as 30 mm in diameter; grades from bed below.

Sandstone: pebbly, hard, weak-yellow ish-orange (10 YR 7/6), thick-bedded, fine-grained; angular and sub-angular chert and quartzite pebbles are as much as 40 mm in diameter, average 3 to 10 mm in diameter; grades from bed below.

Tosi Chert Member of the Phosphoria Formation:

Chert: hard, medium-gray (Af 6), thin- bedded; grades from bed below.

Sandstone: hard, light-olive-gray (5Y 4/2), very thick bedded, fine-grained.

Chert: hard, pale-brown (IOYR 5/2), thin-bedded; contains thin lenses of sandstone in lower 2 ft; contains many columnar bodies of chert and sandstone.

Sandstone: hard, light-brownish-gray (10 YR 6/1), very thick bedded, fine grained; grades from bed below.

Chert: hard, grayish-brown (2.5F4/2), thin-bedded; contains many colum nar bodies of sandstone constituting 30 to 40 percent of bed.

Thick ness (feet)

4. 2

1. 1

. 9

3.0

Cumulativethickness

(feet)

4. 2

5.3

. 9

3.9

SampleAcid in soluble

Radio- metric eV

Chemical U

6.5

1. 3

6.9

1. 6

2. 4

10. 4

11.7

18. 6

20. 2

22. 6


Sappington Canyon, Mont., lot 1357 Continued

Bed Description

Upper tongue of Shedhorn Sandstone: Us-37_________ Sandstone: hard, light-brownish-gray

(IQYR 6/1), very thick bedded, me dium-grained; contains columnar bodies and nodules of chert.

36__-_-_--_ Sandstone: calcareous, medium-hard, light-brownish-gray (10 YR 6/1), very thick bedded, medium-grained; con tains abundant calcareous pelecypod and gastropod shell fragments, phosphatic skeletal fragments, and a few chert pebbles 3 mm in diameter. Fossil-colln. No. 12697.

35_ ________ Sandstone: calcareous, pebbly, medium- hard, weak-yellowish-orange (2.5 Y 7/4), very thick bedded, fine-grained; basal foot of bed contains rounded flat pebbles composed of aphanitic dolomite; entire unit contains lenses and patches of chert and sandstone pebbles averaging 5 mm in diameter and that are as much as 50 mm in diameter; contains scattered patches or lenses of calcareous gastropod and pelecypod fragments and phosphatic skeletal fragments; unit is crossbedded throughout; irregular contact with bed below. Fossil-colln. Nos. 18589 and 18588.


To-34_________ Chert: hard, pale-brown (10 YR 5/2),thick-bedded.

33_________ Dolomite: cherty, medium-hard, light- yellowish-brown (WYR 6/4), thick- bedded, asphanitic; grades from bed below.

32___ ______ Dolomite and chert, interbedded:medium-hard pale-brown (10 YR 6/2) thin-bedded aphanitic cherty dolo mite interbedded with medium-hard pale-brown (10 YR 6/2) thin-bedded dolomite chert. Fossil-colln. No. 18587.

31_________ Chert: hard, light-brownish-gray (10-YR 5/1), thick-bedded.


Rt-30-________ Phosphorite: cherty, medium-hard,thin-bedded.

29_________ Chert and mudstone, interlaminated:hard brownish-black (10 YR 2/1) thin-bedded dolomitic chert inter bedded with medium-hard brownish- black (10 YR 2/1) thin-bedded dolo mitic mudstone.

28. ________ Chert: phosphatic, medium-hard,brownish-gray (10 YR 3/2), thin- bedded; apatite is very coarsely pelletal; contains a few apatite nodules.

27__-__-_-_ Similar to bed Rt-29; grades from bed below.

26^________ Mudstone: dolomitic, medium-hard,grayish-brown (IOYR 4/2), fissile.

25_ ________ Phosphorite: cherty, medium-hard,brownish-gray (10 YR 4/1), thin- bedded, coarsely pelletal and oolitic.

24_ ________ Dolomite: medium-hard, brownish- gray (10 YR 4/1), thick-bedded, aphanitic.




Uranium

Acid in- Radio- soluble metric ell

Chemical U

3. 5

6.2

26. 1

32. 3

9.3 41. 6

16. 0

1.3

6.9

57. 6

58.9

2. 7 68. 5

.2 68. 7 JAP-5483 23. 0 34. 9 0. 005 0. 007

3. 0

8. 0

1. 8

1. 2

71. 7

71. 9

79. 9

81. 7

82. 2

83.4

5482 16. 1 47.3 . 004

5481

5480

5479

2. 0

25.3

1. 2

73. 6

6.0

. 002

.007

. 000

.008


Sappington Canyon, Mont., lot 1357 ContinuedChemical analyses (percent)

Bed Description


Rt-23-________ Mudstone and phosphorite, interlami-nated: soft light-yellowish-brown (WYR 6/4) mudstone interlaminated with soft brownish-gray (WYR 4/1) medium-pellet al argillaceous phos phorite.

22_ ________ Phosphorite: cherty, medium-hard,dark-gray (N 4), thin-bedded, coarsely pelletal and oolitic; con tains a few apatite nodules.

21 _________ Mudstone: phosphatic, dolomitic, soft,pale-brown (WYR 5/3).

20_ ________ Phosphorite: cherty, medium-hard,pale-brown (WYR 6/2), thick-bed ded, coarsely pelletal and oolitic; contains a few apatite nodules in upper part as much as 4 mm in di ameter.

19_ ________ Dolomite: sandy, phosphatic, soft,thin-bedded, aphanitic; apatite is medium pelletal, sand is fine.

18--____-_. Sandstone: dolomitic, soft, light-yellow ish-brown (WYR 6/4), fine-grained.

17_________ Mudstone: dolomitic, soft, grayish- brown (WYR 4/2), thick-bedded.

16_ ________ Phosphorite: cherty, medium-hard,pale-brown (WYR 6/2), thin-bedded, coarsely oolitic and nodular; nodiiles are as much as 10 mm in diameter; contains phosphatic skeletal frag ments.

15-________ Mudstone: dolomitic, medium-hard,thin-bedded.

14_________ Phosphorite: cherty, sandy, hard,brownish-gray (WYR 4/1), thick- bedded, nodular and coarsely oolitic and pelletal; nodules are as much as 20 mm in diameter; sand is fine; contains phosphatic skeletal frag ments.

13_._______ Limestone: cherty, medium-hard, lieht-yellowish-brown (WYR 6/4), thick- bedded, aphanitic.

12_________ Chert: hard, light-brownish-gray(10 YR 5/1) thick-bedded. May be a tongue of Tosi Chert Member of Phosphoric Formation.

Lower tongue of Shedhorn Sandstone: Ls-ll_ ________ Sandstone: hard, very pale brown

(WYR 7/2), very thick bedded, medium-grained; lower 1.0 ft is dolomitic and contains subangular and subrounded quartzite and chert pebbles as much as 20 mm in diam eter; grades from bed below.

Franson and Grandeur Tongues of ParkCity Formation, Undifferentiated:

Pc-10_________ Chert and sandstone: hard pale-brown(WYR 6/2) thick-bedded chert con taining many lenses and stringers of fine-grained sandstone in lower 7 ft and interbeds of dolomite in upper 2.5 ft.

9 _________ Limestone: medium-hard, weak-yel lowish-orange (WYR 7/0), very thick bedded, finely crystalline; grades from bed below.

8_---_____ Chert and sandstone, interbedded:hard yellowish-gray (WYR 8/1) thick-bedded chert containing some interbeds of hard light-gray (N 7) thick-bedded chert.



0. 3 83. 7 JAP-5478

Uranium

.5

Acid in- Radio- Chemical PaOs soluble metric ell U

17.4 30. 7 0. 004

.2 83. 9

.3 84. 2

1. 1 85. 3

85. 8

.4 86. 2

.7 86. 9

.3 87. 2

2. 3 89. 5

.5 90. 0

.9 90. 9

.7 91. 6

3. 0 94. 6

5477

5476

5475

5474

5473

5472

5471

5470

5469

29. 1 18. 8 . 007 0. 006

8.3 48.7 .004 _______

26. 8 18. 3 . 007 . 007

11. 4

6.8

4.6

18.3

30. 3

57.7

64.7

38.9

. 002

.004 _______

.002 _______

. 006 . 005

1. 5 72. 3 . 002

11. 5 59. 0 . 004

9. 5 104. 1

1. 3 105. 4

6. 5 111. 9


Sappington Canyon, Mont., lot 1357 Continued

Bed

Pc-7

6_

Q-4.

Description

Franson and Grandeur Tongues of Park City Formation, Undifferentiated Con.

Dolomite: silty, medium-hard, light- yellowish-brown (WYR 6/4), thick- bedded, aphanitic.

Sandstone: calcareous, pebbly, hard, very pale brown (WYR 7/2), thick- bedded; contains many angular chert fragments as much as 15 mm in diameter.

Dolomite and chert, interbedded: medium-hard, very pale brown (10 YR 7/3), thick-bedded aphanitic dolomite interbedded with hard very pale orange (10 YR 8/2) thick-bedded chert; chert beds constitute 5 percent of unit at base and 60 percent of unit at top.

Quadrant Formation, upper part:Sandstone: dolomitic, medium-hard,

weak-yellowish-orange (10 YR 7/6), thin-bedded, fine-grained; contains chert and quartzite pebbles in lower 3.0 ft that are as much as 5 mm in diameter.

Sandstone: calcareous, medium-hard, weak-yellowish-orange (10 YR 7/6), very thick bedded, medium-grained; uppermost 1.0 ft contains chert and quartzite pebbles as much as 25 mm in diameter; grades from bed below.

Sandstone: calcareous, hard, verv pale brown (WYR 7/2), very "thick bedded, medium-grained; exhibits some small scale gentle crossbedding; grades from bed below.

Sandstone: calcareous, medium-hard, white (N 9), very thick bedded, medium-grained; contains some elongated light-gray (N 7) chert lenses; underlain by about 25 ft of interbedded sandstone and dolomite in beds 3 ft to 5 ft thick.


Thick ness

(feet)

CumulativeUranium

(feet) SampleAcid in- Radio- soluble metric eU

ChemicalU

6. 9 118. 8

5 119. 3

11. 3 130. 6

16. 0 146. 6

6. 0 152. 6

14. 0 166. 6

5. 0 171. 6

North Big Hole Canyon, Mont., lot 1358[Permian rocks measured in hand trenches and natural exposures on north side of Big Hole River in NE }4 sec. 3,T.5S.,R.8W., Madison County, Mont., on northwest limb

of asymmetrical anticline. Beds G-8 through G-14 measured in lower trench, beds G-17 through M-23 in middle trench and beds Rt-26 through To-63 in upper trench. Remainder of beds measured in natural exposure. Exposures in upper trench are poor; so, although the sequence is probably correct, the measured thicknesses, especially in the lower half of the Retort Tongue, may be too small. Beds strike N. 70° E. and dip 20° N. Measured by J. A. Peterson and sampled by Peterson and R. P. Gosman, in June and July 1951. Analyzed for PaOs and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Geol. Survey]

Bed

Us-72_

To-71.

Us-70.

To-69.

Description

Upper member of Shedhorn Sandstone and Tosi Chert Member of Phosphoria For mation, intertongued:

Sandstone: hard, yellowish-gray (10 YR 7/1), thick-bedded, fine-grained; con tains glauconite. About 25 ft of strata are covered between top of bed Us-72 and the lowermost ex posures of the Dinwoody formation.

Chert: hard, medium-gray (N 6), thick- bedded.

Sandstone: hard, light-brownish-gray (WYR 6/1), thick-bedded, fine grained; contains chert nodules and glauconite.

Chert: silty, hard, medium-gray (N 6), thick-bedded; contains glauconite; crossbedded in part.


Thick ness

Cumulativethickness

(feet)

Uranium

SampleAcid in

solubleRadio-

metric eUChemical

U

4. 6 4. 6

9. 0 13. 6

2. 0 15. 6

8. 2 23. 8


North Big Hole Canyon, Mont., lot 1358 Continued


To-68.

Us-67-

To-66.

Us-65.

To-64. 63.

Rt-62.

61.

58-

55.

52.

50_

49-

48.

47.

46.

45.

Bed Description

Upper member of Shedhorn Sandstone and Tosi Chert Member of Phosphoria For mation, intertongued Continued

______-- Chert: sandy, hard, grayish-brown(WYR 4/2), very thick bedded; con tains glauconite.

__--_--_ Sandstone: hard, pale-brown (10F.R 5/3), very thick bedded, fine-grained.

____---_ Chert: hard, medium-gray (N 5), thick-bedded; contains glauconite; slightly sandy in upper few feet.

_____-_- Sandstone: cherty, hard, grayish-brown (WYR 3/2), very thick bedded, very fine grained; contains glauconite.

_____--_ Chert: dark-gray (N 4)______________-__-__-- Chert: dark-gray (AM), thick-bedded;

contains phosphatic skeletal frag ments.


-------- Mudstone: soft, grayish-brown (10F.R4/2), fissile.

-------- Mudstone: soft, brownish-gray (WYR4/1).

-_-__-__ Mudstone: phosphatic, soft, dusky- brown (10 YR 2/2); apatite is finely pelletal.

________ Phosphorite: carbonatic, medium-hard,brownish-black (10 YR 2/1), coarsely pelletal.

_________ Mudstone: carbonatic, soft, dusky- brown (WYR 3/2).

________ Mudstone: soft, dusky-brown (10F.R3/2).

_________ Phosphorite: medium-hard, brownish- gray (WYR 3/1), finely pelletal.

__-__--_ Phosphorite:muddy, soft, dusVy-brown (WYR 3/2), medium-pelletal.

______-- Mudstone: phosphatic, soft, dusky- brown (WYR 2/2); apatite is very finely pelletal.

_____--- Phosphorite: medium-hard, black (N 2), thin-bedded, finely pelletal.

________ Mudstone: soft, dusky-brown (10F.R2/2).

________ Phosphorite: medium-hard, brownish- black (WYR 2/1), thin-bedded, medium-pelletal.

________ Dolomite: phosphatic, medium-hard,dusky-brown (WYR 3/2), aphanitic, apatite is finely pelletal.

Phosphorite: muddy, soft, brownish- gray (WYR 4/1), thin-bedded, finely pelletal.

________ Phosphorite: soft, brownish-black(WYR 2/1), medium-pelletal; grades from bed below.

. ______ Phosphorite: muddy, soft, brownish- black (WYR 2/1), medium-pelletal; grades from bed below.

.__--__-_ Phosphorite: muddy, soft, brownish- black (WYR 2/1), finely pelletal; grades from bed below.

.____ Mudstone: soft, dusky-brown (10F.R3/2); grades from beds below.

.____ Phosphorite: muddy, soft, brownish- black (WYR 2/1), finely pelletal.

Thick- Cumulative ness thickness (feet) (feet)

2. 0 25. 8

2. 0 27. 8

21. 6 49. 4

26. 5 75. 9

4. 0 79. 9 .6 80. 5

1. 0 81. 5

1. 0 82. 5

2. 2 84. 7

.6 85. 3

.5 85. 8

.8 86. 6

.6 87. 2

.7 87. 9

.6 88. 5

1. 3 89. 8

.5 90. 3

1. 8 92. 1

.8 92. 9

.6 93. 5

.8 94. 3

1. 7 96. 0

1. 7 97. 7

.4 98. 1

1. 4 99. 5

Uranium

Sample

JAP-5461

5460

5459

5458

5457

5456

5455

5454

5453

5452

5451

5450

5449

5448

5447

5446

5445

5444

5443

5442

Acid in- Radio- PzOj soluble metric eU

4. 5

2.4

4.5

13.3

15.9

4. 8

4.7

23.9

16. 4

11.7

23. 7

7.7

24. 3

12. 0

19. 4

21. 9

26.3

17.0

6. 3

16.3

82. 4

71. 3

66. 4

45. 4

12. 4

58. 6

60. 7

10. 9

31. 3

42. 3

9.9

49. 7

10.0

8.0

21. 3

20. 9

15.0

32. 6

59.5

31. 7

0. 002

. 003

.002

. 006

.005

.005

. 004

. 007

. 008

. 007

. 007

. 005

.006

. 003

. 007

. 007

. 008

.007

.005

.008

Chemical IT

0. 003

. 004

.005

. 007

. 006

. 005

. 006

. 003

. 005

. 006

. 007

. 009

. 005

. 002

. 006



539


Bed Description


Rt-43_-------- Phosphorite: muddy, soft, brownish- black (10 YR 2/1), medium-pelletal.

42_____---- Mudstone: phosphatic, soft, dusky- brown (10 YR 2/2); apatite is medium pelletal; grades from beds below.

41_-------- Dolomite: medium-hard, brownish- gray (10 YR 4/1), aphanitic; grades from beds below.

40--------- Dolomite: medium-hard, brownish- gray (10 YR 4/1), thick-bedded, aphanitic.

39__------- Dolomite: medium-hard, dusky-brown(10 YR 3/2), aphanitic.

38_-------- Phosphorite:muddy, soft, dusky-brown(10 YR 2/2), medium-pelletal.

37__------- Dolomite: medium-hard, brownish-gray(10 YR 4/1), aphanitic.

36___------ Mudstone: phosphatic, brownish-gray(10yfl3/l).

35--------- Dolomite: medium-hard, brownish- gray (10 YR 3/1), aphanitic.

34_._------ Mudstone: soft, dusky-brown (10 YR3/2).

33_-------- Mudstone: phosphatic, soft, dusky- brown (10 YR 2/2); apatite is medium pelletal.

32__-____-- Dolomite: medium-hard, brownish- gray (10 YR 4/1), thick-bedded, aphanitic.

31-__-----_ Phosphorite: muddy, soft, brownish- gray (10F# 3/1), medium-pelletal.

30--------- Dolomite: medium-hard, pale-brown(10 YR 6/2), aphanitic

29_-------- Phosphorite: muddy, medium-hard,grayish-brown (IOYR 3/2), finely pelletal.

28-_------- Mudstone: phosphatic, medium-hard,grayish-brown (7.5YR 4/2); apatite is medium pelletal.

27__-_-_-_- Phosphorite: muddy, medium-hard, dark-gray (N 3), thick-bedded, medium-pelletal; contains phospha tic skeletal fragments.

26--------- Mudstone: hard, moderate-yellowish- brown (10 YR 5/6), thick-bedded; grades from bed below.

Franson Member of Park City Formation,uppermost bed:

F-25---------- Sandstone: cherty, yellowish-brown.Interval between beds R-24 and F-25 covered and not measured. Fossil-colln. No. 18584.


R-24-__-_._-_ Chert__-_____--------___-____-__-_Meade Peak Phosphatic Shale Tongue of

Phosphoria Formation: M-23--------- Mudstone: medium-hard, pale-brown

(10 YR 5/3), thin-bedded-_________22_--____-_ Mudstone: medium-hard, light-olive-

brown (2.5 Y 5/4), thin-bedded.21---_____- Phosphorite: hard, light-gray (N 7),

thick-bedded, coarsely pelletal and oolitic; contains apatite nodules as much as 25 mm in diameter.

Thick ness (feet)

1.4

2.3

. 4

.7

. 4

. 5

. 6

1. 1

1. 1

. 7

. 4

.7

.5

1. 4

1.5

1. 5

. 5

.5

5.0

3.0

1.2

.8

.6


(feet)

100. 9

103. 2

103. 6

104.3

104. 7

105. 2

105. 8

106. 9

108. 0

108.7

109. 1

109. 8

110.3

111.7

113.2

114.7

115. 2

115. 7

120. 7

123.7

124.9

125.7

126.3

Uranium

Sample

JAP-5441

5440

5439

5438

5437

5436

5435

5434

5433

5432

5431

5430

5429

5428

5427

5426

5425

5411

5410

5409

PzOa

20. 6

14. 0

2.3

2. 5

3.4

17. 6

5. 1

9. 8

3.5

7.9

11. 5

3.3

14.7

2.2

19. 5

13. 8

23.2

. 6

.5

34.0

Acid in- Radio- soluble metric e\J

22. 7

38. 5

5. 0

5. 8

7.7

28. 5

9. 9

39. 3

6. 1

48.9

38. 4

6. 1

27.2

5.5

27.5

38.5

36.0

85. 3

86. 3

10. 0

0. 008

. 006

.002

. 001

. 002

.008

. 003

. 005

. 002

. 006

. 008

. 001

. 006

.001

.006

.004

. Oil

.002

.003

. 007

Chemical U

0.008

.004

. 006

. 005

. 003

. 006

.005

.005

.007

.006



Bed Description

Grandeur Member of Park City Formation: G-20-_-_______ Mudstone: carbonatic, soft, dark-

yellow (2.5 F 6/8), fissile. Fossil- colln. No. 12692.

19____------ Mudstone: dolomitic, medium-hard,light-yellowish-brown (10 YR 6/4), very thick bedded.

18___------- Mudstone: dolomitic, medium-hard,weak-yellowish-orange (10 YR 7/6), thin-bedded.

17___ ------- Mudstone: dolomitic, soft, light-yellowish- brown (IQYR 6/4), thin-bedded.

16--_------- Chert---__________________________(15)-------- Not described-_-_-___--_----_-__-__14_ ____-_-__ Limestone: muddy, soft, thin-bedded _13____--_-_- Limestone: muddy, hard, very pale

brown (10 YR 7/2), very thick bedded.12--_-----_- Dolomite: muddy, hard, light-brown

ish gray (IQYR 6/1), very thick bed ded, aphanitic.

11__________ Mudstone: dolomitic, medium-hard,brownish-gray (IQYR 4/1), very thick bedded; grades from bed below.

10---------- Dolomite: muddy, medium-hard, black(TV 1), very thick bedded, aphanitic; grades from bed below. Fossil-colln. No. 51-JAP-l.

9_____---_-_ Mudstone: dolomitic, medium-hard, grayish-brown (2.5 Y 4/2), very thick bedded; grades from bed below.

8._--__-_-_- Dolomite: muddy, soft, dusky-brown (IQYR 2/2), thin-bedded, aphanitic; grades from bed below.

7__-_-_-__ Dolomite:hard, pale-brown (10F.R6/2), very thick bedded, aphanitic.

6____------- Dolomite: hard, pale-reddish-brown(IQR 5/4), thick-bedded, aphanitic.

5_---------- Dolomite: hard, light-brownish-gray(IQYR 6/1), very thick bedded, aphanitic.

4__-_____- Chert: hard, light-gray (TV 8), thick- bedded.

3_____--_--_ Limestone: medium-hard, pale-reddish- brown (IQR 5/4), very thick bedded, very coarse grained; contains some chert nodules.

2___________ Limestone: medium-hard, pale-reddish- brown (IQR 5/4), thin-bedded, very coarsely crystalline.

Quadrant Formation, uppermost bed: Q-l__-__------ Sandstone: hard, light-brown (7.5YR

6/4), very thick bedded, fine-grained.


Uranium

1. 1 200. 8

. 8 201. 6

2. 8 204. 4

1. 0 205. 4

7. 6 213. 0

4. 3 217. 3

5407


0. 9 127. 2 JAP-,

2. 0 129. 2

3. 3 132. 5

4. 2 136. 7

1. 0 137. 750. 0 187. 7

1. 5 189. 21. 1 190. 3

1. 1 191. 4

3. 4 194. 8

1. 9 196. 7

1. 5 198. 2 5386

1.5 199.7 -_--_-_-__

Acid in- Radio- Chemical soluble metric eV U

0. 8 68. 3 0. 003

.3 69. 0 . 002

CQQA

5388

5387

.3

. 6

. 6

. 3

27. 3

27 n

48.2

35. 3

.002 --___-_

.003 -------

.003 _-__---

.003 __--_--

.1 50. 2 . 004

<. 1 19. 4 . 000


Canyon Creek No. 8, Mont., lot 1S59[Permian rocks measured in hand trench and natural exposure about 1,500 ft northeast of Canyon Creek road on northeast limb of broad syncline in NWH sec. 13, T. 2 S.,

R. 10 W., Beaverhead County, Mont. Beds strike N. 25° W. and dip 38° SW. Measured by J. A. Peterson and sampled by R. F. Gosman, in July 1951. Samplesanalyzed for PjOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

Us-36.

(35). 34_

To-33_

32.

31_

30.

Rt-29.

28_

27_

26.

25.

24.

23.

22.

21.

20. 19.

18.

Description

Upper tongue of Shedhorn Sandstone:Sandstone: hard, light-brownish-gray

(WYR 6/1), very thick bedded, fine grained; sand is slightly more coarse than underlying sands; so, this inter val is probably the uppermost bed of the Shedhorn sandstone. Actual contact with the overlying Dinwoody formation is covered.

Covered: sandstone and chert float- __Sandstone: hard, light-brownish-gray

(10y.R 5/1), fine-grained; interval is partly covered: grades from bed below.


Chert: sandy, medium-gray (N 5), hard; interval is partly covered; grades from bed below.

Sandstone and chert, interbedded: hard medium-gray (N 5) sandstone interbedded with hard medium-gray (N 5) chert; grades from bed below.

Chert: hard, brownish-gray (WYR 3/1); interval is partly covered.

Chert: sandy, hard, dark-gray (N 4),very thick bedded; sand is fine.


Phosphorite: medium-hard, dark-gray (N 3), thick-bedded, coarsely pelletal.

Limestone: soft, light-brownish-gray (WYR 5/1), aphanitic; grades from bed below.

Mudstone: dolomitic, soft, pale-brown (7.5YR 6/2), fissile.

Phosphorite: hard, dark-gray (N 3), thick-bedded, very coarsely pelletal.

Mudstone: soft, pale-brown (IOYR 6/2), fissile.

Phosphorite: medium-hard, dark-gray N 4, thick-bedded, medium-pelletal.

Mudstone: phosphatic, soft, light-olive- brown (2.SYR 5/4); apatite is finely pelletal.

Mudstone: phosphatic, soft, pale-brown (WYR 5/2); apatite is finely pelletal.

Phosphorite: muddy, soft, moderate- yellowish-brown (10 YR 4/4), finely pelletal.

Mudstone: soft, vari-colored-________Mudstone: phosphatic, soft, light-

yellowish-brown (2.5F 6/4); very few pellets are apparent in hand specimen.

Mudstone: phsphatic, hard, medium- gray (N 5), thick-bedded; apatite is very finely pelletal; contains a few phosphatic skeletal fragments; grades from bed below.


Uranium

1. 2

SampleAcid in- Radio- Chemical

soluble metric eU U

12. 0 20. 012. 0 32. 0

25. 0 57. 0

5.0

12. 0

2.0

.9

q

. 4

. 9

Q

. 4

2. 2

1. 5

3. 0

3. 52. 0

62. 0

74. 0

76.0

76.9

77 S

7R 9

79. 1

7Q 4

79.8

82. 0

83. 5

86. 5

90. 092. 0

JAP-5424

5223

5422

5421

5420

5419

5418

5417

5416

54155414

31. 5

1 9

.7

29. 0

3. 6

27.3

20. 6

13. 6

23. 7

4. 510. 5

15. 8

16. 1

64 Q

4.9

59. 3

5. 3

22. 9

47. 2

24. 5

64. 554. 1

0. 006

. 001

. 002

. 006

. 004

. 007

.007

. 006

. 006

. 004

. 005

0. 006

.005

. 007

. 004

. 004

.005

.002

93. 2 5413 13. 6 38. 3 . 005 . 003

709-931 O-64 18


Canyon Creek No. 3, Mont., lot 1859 ContinuedChemical analyses (percent)

Bed Description

Franson and Grandeur Members of ParkCity Formation, undifferentiated:

Pc-17_________ Sandstone: phosphatic, medium-hard,light-brownish-bray (10 YR 5/1), thick-bedded, fine-grained; apatite is finely pelletal; contains a few phosphatic skeletal fragments; grades from bed below.

16 _________ Limestone: sandy, medium-hard,medium-gray (N 5), very thick bedded; sand is fine; contains some calcareous shell fragments; grades from bed below. Fossil colln. No. 12694.

15_________ Sandstone: medium-hard, medium- gray (N 6) very thick bedded, fine grained.

14. ________ Dolomite: medium-hard, dark-gray(N 4), very thick bedded, aphanitic; small chert nodules constitute about 10 percent of bed.

13_ ________ Dolomite: medium-hard, dark-gray(N 4), very thick bedded, aphanitic; light-brownish-gray (WYR 5/1), chert nodules and irregular masses constitute about half of unit.

12..________ Dolomite: silty, medium-hard, light- brownish-gray (IQYR 5/1), thick- bedded, aphanitic; small chert nod ules constitute about 10 percent of unit; cross-bedded near base.

(11) ------ Covered... ________________________10_______ Dolomite: medium-hard, medium-

gray (N 5), very thick bedded, aphanitic; 50 percent of unit consists of irregular masses of light-brown (7.5 YR 5/4 chert.

9_________ Dolomite: medium-hard, medium-gray(N 5), very thick bedded, aphanitic; contains some pale-brown (7.SYR 6/2) chert nodules; grades from bed below.

8_________ Dolomite: medium-hard, medium-gray(N 6), very thick bedded, aphanitic.

(7) _________ Covered___________________________6_________ Dolomite: medium-hard, medium-gray

(N 6) very thick bedded, aphanitic.(5).______ Covered: medium-gray (2V 5) dolomite

float. 4_________ Dolomite: hard, medium-gray (2V 6),

very thick bedded, aphanitic; about 25 percent of unit consists of light- brownish-gray (10 YR 5/1) chert nodules.

(3)_._______ Covered: moderate-yellow (2.5F 7/6)mudstone float.

2________ Sandstone: cherty, hard, light-brown ish-gray (10 YR 5/1), very thick bedded, very fine grained; contains some medium quartz sand.

!_________ Dolomite: hard, medium-gray (N 5),aphanitic; underlain by hard yellow ish-gray sandstone of Quadrant Formation.

Thick- Cumulativeness thickness(feef) (feet) Sample

0. 7 93. 9 JAP-5412

Uranium

4. 5 98. 4

6. 0 104. 4

12. 7 117. 1

18. 0 135. 1

5. 0 140. 1

16. 5 156. 62. 0 158. 6

7. 4 166. 0

5. 7 171. 7

7. 0 178. 73. 0 181. 7

7. 0 188. 7

7. 0 195. 7

6. 3 202. 0

1. 5 203. 5

6. 0 209. 5

PtOt

15.9

Acid in- Radio- soluble metric eU

45. 3 0. 005

ChemicalU

0.003

STRATIGRAPHY AND PETROLOGY, PERMIAN ROCKS OF SOUTHWESTERN MONTANA 543London Ridge, Mont., lot 1361

[Meade Peak Pbosphatic Shale Tongue of Phosphoria Formation measured and sampled in bulldozer trench in SWJ4 sec. 27, T. 12 S., R. 2 W., Beaverhead County Mont Beds strike east-west and dip 25° S. Measured by J. A. Peterson and sampled by Peterson and R. F. Qosman, in August 1951. Samples analyzed for PsO 5 and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Qeol. Survey]


Bed

M-7.

G-l.

Description

Lower member of Shedhorn Sandstone, basal bed:

Sandstone: hard, light-brownish-gray (IOYR 6/1), thick-bedded, fine grained. Overlying beds are cov ered.

Meade Peak Phosphatic Shale Tongue of Phosphoria Formation:

Phosphorite: cherty, medium-hard, light-brownish-gray (IOYR 6/1), thin-bedded, coarsely pelletal.

Phosphorite: sandy, cherty, medium- hard, light-brownish-gray (IOYR 6/1), thick-bedded, very coarsely pelletal.

Phosphorite: medium-hard, light- brownish-gray (IOYR 6/1), thick- bedded, very coarsely pelletal.

Phosphorite: sandy, medium-hard, light-brownish-gray (10 YR 6/1), thick-bedded, very coarsely pel letal.

Phosphorite: medium-hard, light- brpwnish-gray (IOYR 6/1), very thick-bedded, very coarsely pelletal.

Phosphorite: medium-hard, light- brownish-gray (IOYR 6/1), thick- bedded, very coarsely pelletal.

Grandeur Tongue of Park City Formation, uppermost bed:

Chert: hard, medium-gray (N 6), thick-bedded.


(feet) (feet)

3. 0

1. 1

1. 4

1. 1

1. 2

. 6

3. 0

3.6

4. 7

6. 1

7.2

*. 4

9.0

Uranium

SampleAcid

insolubleRadiometric

eUChemical

U

3. 2 JAP-5489

5488

5487

5486

5485

5484

19. 3

18. 7

41. 5 0. 003

27.6

28. 7

26.3

46. 4

18.0

20.5

18.3

20. 6

004

005

004

005

005

0.005

.005

.006

Indian Creek, Mont., lot 1362[Permian rocks measured from natural exposures on north side of Indian Creek Canyon in SWH sec. 21, T. 8 S., R. 2 E., Madison County, Mont., by R. F. Qosman and

Retort Member sampled by J. A. Peterson, in August 1951. Section revised by R. W. Swanson in August 1955 and 1956. Beds strike N. 20°-25° W. and dip about 25° NE. Analyzed for P2O5 and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Qeol. Survey]


Bed

D-49.

Us-48.

47.

46.

Description

Dinwoody Formation, basal bed:Carbonate rock: hard, thick-bedded,

aphanitic, pale-brown (IOYR 6/2), weathers to darker brown; basal 0.3 ft muddy and thin-bedded to fissile; probably composed largely of dolo mite; basal contact sharp.

Upper member of Shedhorn Sandstone:Sandstone: hard, thick-bedded to mas

sive, fine-grained, pale-brown (IOYR 5/2); contains numerous small chert nodules and thin streaks of very finely sandy to cherty carbonate rock; commonly, 0.2 ft medium- bluish-gray (5B 5/1) to light-bluish- gray (5B 7/1) chert at top, and top foot generally lighter gray.

Chert: hard, wavy-bedded, white (AT 9).

Sandstone: hard, massive, fine- to me dium-grained, light-brownish-gray (IOYR 6/1); contains 1-ft cherty zone in lower middle, numerous yellowish- gray (IOYR 7/1) chert nodules, and cherty columnar concretions.

Thick ness (feet)

40. 0

Curmtlativethickness

(feet)

40. 0

Uranium

SampleAcid in


metric eU U

12.8 12.8

1.0

5.6

13.8

19.4


Indian Creek, Mont., lot 1362 ContinuedChemical analyses (-percent)

Bed Description


Us-45_ ________ Chert and sandstone, interbedded:chert dominant in middle; hard thin- to thick-bedded; white (N 9) chert interbedded with fine-grained very pale brown (IQYR 7/2) sandstone that contains many dark grains; chert contains many spicules and apatite canal fillings, apatite rims on quartz and chert grains, apatite pel lets, and small carbonate rhombs and limonite cubes after pyrite.

44_________ Sandstone: hard, massive, medium- grained, light-brownish-gray (IQYR 5/1- 6/1); contains shell fragments and many small lenses, flat pebbles, and irregular streaks of dense finely sandy carbonate rock.

43. _ _______ Sandstone: carbonatic,1 hard, massive,fine- to coarse-grained, light-brown ish-gray (IQYR 6/1) to pale-brown (IQYR 6/2); contains numerous len ticular zones of flat-pebble carbonate conglomerate and many dark apatite pellets; numerous silicified fossils project form cliff face.

42_________ Chert: hard, thin- to thick- and wavy- bedded, light-brownish-gray (10 YR 6/1); contains concentrically banded columns; top \}i ft nodular with shaly matrix, and top one-half ft contains carbonate-rock lenses.

41 _________ Chert and sandstone: hard laminatedwhite chert capped by about half a foot of fine sandstone, with very irregular contact between; basal contact irregular.

40_________ Sandstone: hard, massive, fine- to med ium-grained, pale-brown (IQYR 6/2); abundant but incomplete quartz overgrowths, coarsely crystalline car bonate matrix, and apatite pellets.

39_________ Sandstone: hard, massive, fine- tomedium-grained, pale-brown (7.5YR 6/2); top half foot, chert; contains shell fragments.

38_________ Sandstone: hard, massive, fine-grained,pale-brown (2.5 Y 5-6/2); contains much fine black material (solid hy drocarbon?) ; top foot contains white- weathering cherty columnar concre tions.


To-37_________ Chert: hard, thin- to thick-bedded,dark-gray (N 3} grading upward to brownish gray (IQYR 4-5/1); top 10 ft notably lighter and thicker bedded.


Rt-36_________ Phosphorite and mudstone: one bedhaving lateral gradations in lithology; hard, medium coarsely pelletal, brownish-gray (IQYR 3/1); contains phosphatic shell fragments.

35_________ Carbonate rock: medium-hard, thin- bedded, dense, brownish-gray (IQYR 4/1).

34_________ Phosphorite: soft, fissile to thin-bed ded, finely to coarsely oolitic-pelletal, brownish-black (IQYR 2/1); contains considerable amounts of organic matter.


1. 8 21. 2

Uranium

Sample P.OsAcid in

solubleRadio-

metric eUChemical

U

3. 8 25. 0

2. 7 27. 7

6. 4 34. 1

1. 0 35. 1

18. 7 53.

6. 5 60. 3

3. 2 63. 5

42. 0 105. 5

. 3 105. 8 RFG-5497 23. 9 32. 3 0. 008 0. 007

.4 106.2 5496 1.7 10.3 .001 _______

2. 0 108. 2 5495 23. 9 16. 3 . 008 . 007


Indian Creek, Mont., lot 1362 ContinuedChemical analyses (percent)

Bed

Rt-33_.

32..

31..

30_.

29__

Ls-28.

27.

26.

25.

24.

F-23_.

22.

Description

Retort Phosphatic Shale Tongue of Phos- phoria Formation Continued

Phosphorite: medium-hard, thick-bed ded, finely to coarsely oolitic, brown ish-black (10 YR 2/1); contains phosphatic shell fragments.

Mudstone: medium-hard, fissile to thin- bedded, brownish-black (10 YR 2/1); contains a few shell fragments and considerable amounts of organic matter.

Dolomite: hard, very finely crystal line, dusky-brown (WYR 2/2).

Mudstone and phosphorite: 0.4 ft soft fissile grayish-brown (10 YR 4/2) mudstone overlain by 0.3 ft soft thin- bedded medium coarsely oolitic black (N 2) sheared phosphorite; both contain much organic matter.

Mudstone: phosphatic, medium-hard, thin-bedded, grayish-brown (WYR 4/2); contains much irregularly dis tributed fluorite, some purple, generally as replacement of siliceous sponge spicules or phosphate matrix, but some as replacement of quartz beneath earlier rim of apatite; apatite lighter colored near fluorite and commonly recrystallized near fluorite that is in con tact with or has replaced silica; con tains phosphatic shell fragments.

Lower member of Shedhorn Sandstone; contains tongue of Franson Member of Park City Formation:

Sandstone: hard, thick-bedded to mas sive, fine- to medium-grained, light- brownish-gray (10F.R 6/1); contains numerous cherty concretions and phosphatic shell fragments.

Sandstone and carbonate rock: car bonate rock at base grades upward into sandstone like that of bed Ls-28; numerous sandstone columns at base and irregular pebblelike sandstone masses above.

Chert: hard, thin-bedded, brownish- gray (10 YR 4/1).

Sandstone: hard, massive, fine- to me dium-grained, light-brownish-gray to pale-brown (10[YR 5/1 to 6/2); con tains a prominent and persistent chert concretion and quartzite-pebble zone in lower third and numerous other chert concretions, some normal to bedding.

Mudstone: sandy, soft, fissile to thin- bedded, pale-brown (7.5 YR 5/2); sand, fine to medium.

Carbonate rock: sandy, hard, massive, finely crystalline, yellowish-gray (1QYR 7/1); probably dolomite; apatite shell fragments in top 2 ft; very sandy in basal foot, which is overlain by half-foot zone contain ing small well-rounded chert, quartzite, and carbonate pebbles; pebbles also at top and 3 ft below top; some chert pebbles rich in sponge spicules.

Carbonate rock: very sandy, hard, yellow ish-gray (10 YR 7/1); sand, fine to coarse; contains quartz, chert, and apatite grains and phosphatic shell fragments; thickness ranges from 0-0.4 ft; irregular basal contact.

UraniumThick- Cumulativeness thickness(feet) (feet) Sample P20 5

Acid in- Radio- soluble metric ell

ChemicalU

1. 1 109. 3 RFG-5494 31. 9 3. 9 0. 010

1. 0 110. 3

. 4 110. 7

.7 111.4

.6 112. 0 5490

5493 3.8 63.3 .004 _______

5492 1.6 8.1 .001 _______

5491 19. 5 26. 5 . 009 0. 008

15. 0 47. 5 . 009 . 007

2. 8 114.

1. 3 116. 1

2. 4 118. 5

9. 3 127. 8

4. 0 131. 8

7. 2 139. 0

3 139. 3


Indian Creek, Mont., lot 1362 Continued

Bed Description

Lower member of Shedhorn Sandstone; con tains tongue of Franson Member of Park City Formation Continued

Ls-21 _________ Sandstone: carbonatic, hard, massive,fine-grained, yellowish-gray (10 YR 8/1); locally very carbonatic and contains many clastic carbonate grains, some as much as 6 mm in

diameter; contains apatite shell- fragment pellets.

20_________ Chert: hard, laminated to massive,yellowish-white (10 YR 9/1); locally sandy.

19__---____ Sandstone and chert, interbedded: hardlaminated yellowish-white (10 YR 9/1) locally sandy chert, interbedded with fine- to medium-grained very pale brown (10 YR 7/2) sandstone containing phosphatic shell frag ments.

18__-_-____ Sandstone: hard, thick-bedded, fine grained, yellowish-gray (IQYR 7/1); contains layers and streaks of lami nated carbonate rock at 0.8 and 1.6 ft above base.

17_ _-_____- Chert: sandy, hard, laminated, yellow ish-white (IQYR 9/1); contains lam inae of cherty sandstone; sand is fine and contains apatite pellets, spicule canal fillings, and clear grains (prob ably water-worn shell fragments); chert generally spicular; zircon and tourmaline grains common in sand

stone.16.___--_-. Sandstone: hard, thick-bedded, fine

grained, yellowish-gray (10 YR 7/1); contains thin carbonate layers near base and small chert and quartzite pebbles at middle; contains grains of spicular chert and light-brown apa tite (lowest horizon at which phos phate and other Phosphoria indica tors found).

Grandeur Tongue of Park City Formation: G-15__________ Carbonate rock: hard, massive, apha-

nitic, yellowish-gray (2.5 Y 8/2); con tains considerable amounts of very fine sand; irregular basal contact.

14__________ Sandstone: hard, massive, cross-bed ded in part, fine-grained, very pale orange (IQYR 8/2); locally, streaks of coarse gritty sand; extensive over growths on quartz.

13____-_____ Dolomite: hard, thick-bedded, dense,yellowish-gray (2.5 Y 8/1).

12._________ Dolomite: hard, massive, finely crys talline, yellowish-gray (IQYR 7/1); contains poorly preserved fossils at top and bottom.

!!__________ Sandstone: hard, massive, fine- to veryfine-grained, yellowish-white (IQYR 9/1); gritty at base, containing numer ous round masses of chalcedonic chert in rhombic carbonate matrix and characterized by dust lines that commonly delineate crystal outlines, with angles usually nearly 90° as rr' of quartz, and suggesting zonal growth.

10_-________ Dolomite: hard, thick-bedded, apha-nitic, yellowish-gray (10 YR 8/1).

9__________ Sandstone: hard, massive, fine-grained,very pale orange (IQYR 8/2); locally crossbedded.



14. 2 153. 5

Sample PtOs,Acid in

solubleRadio-

metric eUChemical

U

3. 4 156. 9

2. 6 159. 5

2. 9 162. 4

3. 9 166. 3

1. 0 167. 3

2. 7 170. 0

4. 5 174. 5

2. 0 176. 5

1. 0 177. 5

5. 3 182. 8

3. 0 185. 8

3. 7 189. 5


Indian Creek, Mont., lot 1362 Continued


Uranium Thick- Cumulativeness thickness Acid in- Radio- Chemical

Bed Description (feet) (feet) Sample P_O5 soluble metric eV U


G-8__________ Dolomite: silty, hard, massive, apha- 2.0 191.5 __________ ______ ______ ______nitic, very pale orange (10 YR 8/2); basal part not well exposed.

7__________ Sandstone: hard, massive, very fine 8.2 199.7 __________ ______ ______ ______ _______to medium-grained, yellowish-gray (10YJ? 8/1); locally crossbedded; ex tensive overgrowths on quartz grains.

6__________ Dolomite: hard, aphanitic, yellowish- .5 200.2 __________ ______ ______ ______ _______gray (10F.R 8/1); crossed by calcite veinlets.

5_-________ Sandstone: hard, very fine to fine- 1.0 201.2 __________ ______ ______ ______ _______grained, yellowish-gray (10FR 8/1).

4__________ Dolomite: silty, hard, aphanitic, yel- 1.0 202.2 __________ _ ____ ______ ______ _______lowish-gray (10 YR 7/1).

3__________ Sandstone: hard, massive, very fine 1.3 203.5 __________ ______ ______ ______ _______to medium-grained, yellowish-gray (2.5F 7/2).

(2)_________ Covered___________________________ 5.8 209.3 -_______._ ______ ______ ______ _______Quadrant Formation, top part:

Q-l------_-__- Sandstone and dolomite: sandstone, 7.0 ______ __________ ______ ______ ______ _______hard, massive, fine-grained, pale- yellowish-orange (2.5F 9/4), crossbedded, dominant overgrowths on quartz grains; hard dense yellowish- gray (10 YR 8/1) dolomite in top foot.

Cinnabar Mountain, Mont., lot 1363

[Permian rocks measured from natural exposures on east side of Cinnabar Mountain, sec. 31, T. 8 S., R. 8 E., Park County, Mont., by J. A. Peterson, and Retort Member of Phosphoria Formation sampled by R. F. Gosman, in August 1951. Beds strike about N. 50° W. and dip 75° S W. Location of contact between Dinwoody and Shedhorn Formations is uncertain. Bed 21 is placed in the Shedhorn on the basis of the fossil collection. Analyzed for P.Os and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Uranium Cumulative

Thickness thickness Acid Radio- Bed Description (feet) (feet) Sample PsO. insoluble metric eU

Dinwoody Formation, basal beds only: D-23__ _______ Dolomite: muddy, medium-hard, poorly to thin- 1.5 ______ __________ ______ ______ _______

bedded, light-gray (N 7); gradational basal contact.

22__________ Limestone: hard, poorly bedded, aphanitic, 2.0 ______ __________ ______ ______ _______medium-gray (N 5).

Upper member of Shedhorn Sandstone; contains two tongues of Tosi Chert Member of Phosphoria Formation:

Us-21_________ Limestone: medium-hard, massive, aphanitic, 4.8 4.8 __________ ______ ______ _______medium-gray (N 6), weathers pale-brown, 10YR 6/2. Fossil-colln. Nos. 12695and 18844.

20---______ Sandstone: eherty, hard, thin-bedded; dark- 6.5 11.3 __________ ______ ______ _______gray (N 3)

To-19_________ Chert: hard, poorly bedded to massive, medium- 11.8 23.1 __________ ______ ______ _______gray (N 5); contains irregular masses and stringers of light-olive-gray (5Y 6/1) dolomite and some black crystalline calcite.

US-18 ______ Sandstone: calcareous, hard, massive, fine- to 7.2 30.3 __________ ______ ______ _______very fine grained, light-brownish-gray (10 YR 6/1); locally eherty; contains 30 to 40 percent of finer grained sandstone columns.

17_________ Dolomite: medium-hard, massive, aphanitic, 2. 5 32. 8 __________ ______ ______ _______yellowish-gray (5Y 7/1); contains elongate nodules and columns of coarsely crystalline calcite containing small quartz grains and scattered glauconite grains.

To-16_________ Chert and sandstone: hard massive very fine 8.0 40.8 __________ ______ ______ _______grained pale-brown (10 YR 6/2) sandstone containing very abundant columnar concre tions and elongate nodules of sandy chert (50 to 60 percent of rock).


Cinnabar Mountain, Mont., lot 1863 Continued


Bed

Us-15-

Rt-14.

13.

11.

10.

7.

6.

5.

4_

Ls-3_

Description

Upper member of Shedhorn Sandstone; contains two tongues of Tosi Chert Member of Phosphoria Formation Continued

Sandstone and chert: hard massive grayish- brown sandstone (10 YR 4/2) containing chert columns (constituting 50 percent of rock) up to 4 ft long and nodules similar to those in bed above; top foot contains angular fragments of chert but no concretions.

Retort Phosphatic Shale Tongue of Phosphoria formation:

Chert and mudstone, interbedded': hard finely sandy chert and soft calcareous mudstone, both brownish-gray (10 YR 3/1).

Limestone and chert: muddy hard dense me dium- to dark-gray (N 4) limestone containing very abundant (50 percent) columnar concre tions of sandy chert.

Mudstone: calcareous, soft, fissile, brownish- gray (10y.R 3/1); contains annular-ringed columnar chert concretions and scattered small crystals of selenite.

Phosphorite: muddy, medium-hard, thick- bedded to massive, brownish-black (10 YR 2/1); contains fossil fragments and quartz sand.

Carbonate rock: phosphatic, hard, thin- to thick-bedded, medium-gray (N 5); contains abundant phosphatic shell fragments.

Phosphorite: muddy, soft, poorly bedded, brownish-gray (1QYR 3/1); contains abundant disseminated phosphatic shell fragments and columns composed of phosphatic shell frag ments; concretions; arbitrary basal contact.

Phosphorite: like bed Rt-9_____________---_-Phosphorite: like bed Rt-9, but less muddy;

apatite resinous to bluish.Mudstone: phosphatic, carbonatic, soft, fissile

to thin-bedded, brownish-black (1QYR 2/1); phosphate chiefly as shell fragments in columnar concretions, which are also sandy.

Phosphorite: sandy, medium-hard, brownish- gray (IQYR 3/1); phosphate as in bed Rt-6; gradational basal contact.

Conglomerate: phosphatic, hard, light-brownish- gray (IQYR 5/1); chert and quartzite pebbles as much as 3 in. in diameter, average 3/4 in.; matrix is quartz sand and phosphatic shell fragments; gradational basal contact.

Lower member of Shedhorn Sandstone:Sandstone: calcareous, hard, thick-bedded to

massive, fine- to medium-grained, very light gray (N 8); conglomeratic at top with pebbles as much as 1 in. in diameter; grains not well rounded, immersed in dusty carbonate matrix; contains apatite pellets and shell fragments and small orthoclase grains altered to calcite; basal contact sharp and fairly plane.

Quadrant Formation, top beds:Sandstone: calcareous, hard, massive, fine- to

medium-grained, medium-gray (N 5); con tains numerous very fine grains of orthoclase that are commonly altered to calcite around edges; somewhat irregular basal contact.

Sandstone: hard, massive, fine-grained, medium- gray (N 5); prominent overgrowths on quartz; scattered small orthoclase grains mostly altered to calcite; arbitrary basal contact.


(feet) (feet)

7. 0 47.

Sample

Uranium

Acid Radio- PzOs insoluble metric eU

1.9

5. 0

1. 3 49. 1

2. 0 51. 1

.8 51.9

2. 3 54. 2

1. 0 55. 2

2. 2 57. 4

1. 7 59. 11. 5 60. 6

1. 4 62. 0

.7 62. 7

1. 0 63. 7

3. 0 66. 7

JAP-5530

5529

5528

5527

5526

5519

55185517

5516

5499

5498

2. 1 72. 7 0. 000

3. 4 71. 9 . 001

4. 9 64. 5 . 001

19. 9 35. 8 . 002

8. 3 9. 3 . 001

21. 6 23. 03 . 004

21. 3 23. 723. 4 17. 5

12. 6 32. 5

16. 8 36. 3

12. 4 49. 6

. 003

. 002

. 004

. 003

. 003


North Boulder Creek, Mont., lot 1364

[Permian rocks measured in natural exposure on north side of road in NEJ4 sec. 4, T. 2 N., R. 2 W., Jefferson County, Mont. Beds strike N. 20° W. and dip 45° NE. Meas ured by R. F. Gosman and sampled by J. A. Peterson, in August 1951. Analyzed for PzOs and acid insoluble by U.S. Bur. of Mines and for uranium by U.S. Geol. Survey]


Bed

34.

33.

Us-32_

To-3l_

30-

29-

28.

27_

Us-26_

To-25-

24.

23.

22-

21.

20.

19.

18.

Ls-17.

16-

15-

14.

Pc-13.

12-

Description

Ellis Group, lower part:Sandstone: medium-hard, light-yellowish-brown

(IOYR 6/4), fine-grained.Conglomerate: sandy, hard, very thick bedded;

consists of subrounded pebbles and cobbles as much as 0.5 ft in diameter composed of chert, quartzite, and phosphatic(?) chert in a salt and pepper sandstone matrix; irregular contact with bed below.

Tosi Chert Member of Phosphoria Formation; thin sandstone beds at top and middle may be tongues of Shedhorn Sandstone.

Sandstone: hard, pale-brown (IOYR 6/2), thick- bedded, fine-grained; grades from bed below.

Chert: brittle, pale-brown (IOYR 5/3), thin- bedded.

Chert: sandy, hard, brownish-gray (IOYR 4/1), thick-bedded; sand is very fine.

Chert: hard, brownish-gray (iOYR 4/1), thick- bedded.

Chert: muddy, medium-hard, very pale orange (IOYR 9/2), thin-bedded; rock is light and porous and may have originally contained carbonate.

Chert: hard, brownish-gray (IOYR 4/1), thick- bedded; grades from bed below.

Sandstone: hard, grayish-brown (2.5F 3/2), thick-bedded, fine-grained.

Chert: hard, yellowish-gray (5F 7/2), thin- bedded.

Chert: hard moderate-yellowish-brown (IOYR 5/6) thick-bedded chert interbedded with hard moderate-yellowish-brown (IOYR 5/6) thin- bedded muddy chert; contains 0.2-ft zone of white phosphatic nodules 5.0 ft above base of unit.

Chert: phosphatic, hard, light-brownish-gray (IOYR 5/1), thick-bedded; apatite is skeletal, medium pelletal, and nodular; nodules are as much as 20 mm in diameter.

Mudstone: cherty, yellowish-gray (2.5F 7/2), thin-bedded; rock is light and porous and probably originally contained carbonate.

Chert: phosphatic, hard, brownish-gray (IOYR 4/1), thin-bedded; apatite is skeletal, medium pelletal, and nodular; nodules are as much as 10 mm in diameter.

Chert: hard, yellowish-gray (IOYR 8/1), thin- bedded.

Chert: hard, grayish-brown (IOYR 4/2), thick- bedded.

Chert: hard, light-yellowish-brown (IOYR 6/4). thin-bedded; lower 15 ft of unit is poorly exposed.

Lower tongue of Shedhorn Sandstone:Sandstone: hard, yellowish-gray (IOYR 7/1),

thick-bedded, medium-grained.Chert: sandy, hard, pale-brown (2.5F 6/2),

thick-bedded.Sandstone: cherty, hard, yellowish-gray (2.5F

7/2), very thick bedded, very fine grained.Chert: sandy, hard, yellowish-gray (2.5F 7/2),

thick-bedded; sand is medium.Park City Formation; probably equivalent to

Grandeur member:Dolomite and sandstone: unit is mostly covered;

float consists of dolomite and weathered dolomitic sandstone.

Dolomite: medium - hard, weak - yellowish - orange (2.5 Y 7/4), thick-bedded.


(feet) (feet)

15. 0

1. 8

7. 2

1. 4

1. 2

2.0

19. 0

5.4

5. 6

5. 0

20. 0

2. 7

15.0

22.5

22.9

24.9

25.2

44. 2

49. 6

6. 3 55. 9

61. 5

66. 5

86. 5

89. 2

Sample PaOs

Uranium

Acid Radiometrii insoluble «U

8.0

8. 8

9.0

10.4

13. 2

13. 9

15. 1

20. 9

21. 7 RFG-5533 16. 4 52. 5 0. 003

5532 14. 1 59.0 001

5531 4. 3 83. 4 001


North Boulder Creek, Mont., lot 1364 Continued


Bed

Pc-11.

Description

Park City Formation; probably equivalent to Grandeur member Continued

Mudstone: soft, moderate-yellow (2.5 Y 7/6), fissile.

Sandstone: medium - hard, weak - yellowish - orange (2.5Y 7/4), thick-bedded, fine-grained.

Sandstone: calcareous, soft, weak-yellowish- orange (2.5F7/4), thin-bedded, fine-grained.

Sandstone: calcareous, pebbly, medium-hard, moderate-yellow (2.5F 7/6), medium-grained; chert pebbles are as much as 60 mm in diame ter and average 15 mm in diameter.

Sandstone: silty soft weak-yellowish-orange (2.5F 7/4) very fine grained sandstone at base grades into medium-hard weak-yellowish- orange (2.5F 7/4) fine-grained sandstone at top; unit is poorly exposed.

Sandstone: medium-hard, moderate-yellow (2.5F 7/6), thick-bedded, fine-grained.

Sandstone: hard, yellowish-gray (2.5F 8/2), very thick bedded, fine-grained.

Sandstone: silty, soft, moderate-yellow (2.5F 7/6), very fine grained.

Sandstone: medium-hard, moderate-yellow (2.5F 7/6), thick-bedded, very fine grained.

Sandstone: hard, yellowish-white (2.5F 9/2), thick-bedded, medium-grained.

Sandstone: silty, calcareous, soft, weak-yellow ish-orange (2.5F 7/4), very fine grained; unit is poorly exposed; underlain by hard yellow ish-gray (10FR 7/1) fine-grained sandstone of Quadrant Formation.

Thickness (feet)

0.6

1. 6

4.3

Cumulativethickness

(feet)

89.8

90.2

91.8

96. 1

4. 7 100. 8

. 7 101. 5

2. 3 103. 8

3. 2 107. 0

1. 0 108. 0

1. 0 109. 0

6.3 115.3

SampleAcid

insoluble

Uranium

Radio- metric eV

South Boulder Creek, Mont., lot 1365

[Permian rocks measured in hand trench and natural exposure about 200 ft above and west of Jack Creek in NW}4 sec. 10, T. 1 S., R. 3 W., Madison County, Mont. Beds strike east-west and dip 35° N. Measured by J. A. Peterson and sampled by R. F. Qosman, in August 1951. Analyzed for PjO? and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Qeol. Survey]


Bed

E-47-

(46).

45_.

(44). 43.

(42).

To-41_

40_

39-

38.

Description

Ellis Group, basal part: lLimestone: medium-hard, light-brownish-

gray (10 YR 6/1); contains fragments of oyster shells.

Covered: oolitic-limestone and chert float.

Sandstone: hard, yellowish-gray (10 YR 8/1), thick-bedded, fine-grained.

Covered--___-_-_______-_________--Sandstone: hard, yellowish-gray (1QYR

8/1), thick-bedded, medium-grained; contains some pebbles as much as 30 mm in diameter.

Covered: yellowish-gray (WYR 7/1), fine-grained sandstone float. May be Shedhorn Sandstone.


Chert: hard, pale-brown (10 YR 5/2), thin-bedded.

Sandstone: phosphatic, hard, pale- brown (10 YR 5/2), thick-bedded, fine-grained; contains a few phos phatic skeletal fragments.

Chert: hard, very pale brown (10 YR 7/2), thin-bedded.

Chert: phosphatic, hard, light-browu- ish-gray (WYR 5/1), thick-bedded; apatite is medium pelletal; contains a few phosphatic skeletal fragments.


(feet) (feet)

Uranium

15.0

1.0

3.0 3.0

7.0

8.3

1.0

11. 0

Sample P 305Acid


eV U

8. 3

9.3

20. 3

20. 7 JAP-5569 14. 4 59. 9 0. 001

See footnote at end of ta ble.


South Boulder Creek, Mont., lot 1365 Continued

Bed

To-37_

36_

35_

34_

33_

32.

31

Rt-30_

29_28-

Description

Tosi Chert Member of PhOsphoria Forma tion Continued

Chert: dolomitic, medium-hard, light- yellowish-brown (10 YR 6/4), thin- bedded.

Chert: phosphatic, hard, brownish- gray (WYR 4/1), thick-bedded; apa tite is finely pelletal; contains a few phosphatic skeletal fragments.


Phosphorite: sandy, cherty, hard, light-brownish-gray (10 YR 5/1), thick-bedded, finely pelletal; con tains phosphatic skeletal fragments and a few apatite nodules as much as 20 mm in diameter.

Dolomite: cherty, hard, brownish-gray (10 YR 4/1), thick-bedded, aphanitic.

Phosphorite: cherty, hard, light-brown ish-gray (WYR 5/1), thick-bedded, medium-pelletal and oolitic; contains phosphatic skeletal fragments and apatite nodules as much as 10 mm in diameter; grades from bed below.

Chert: hard, light-brownish-gray (10YR 5/1), thin-bedded.

Retort Phosphatic Shale Member of Phos- phoria Formation:

Mudstone: medium-hard, brownish- black (10 YR 2/1), thick-bedded.



(feet) (feet)

Uranium

____ Mudstone: medium-hard, brownish-black (10 YR 2/1), thick-bedded.

27-_--_-___ Mudstone: medium-hard, brownish-black (10 YR 2/1), thin-bedded.

26. ________ Phosphorite: cherty, medium-hard,light-brownish-gray (10 YR 5/1),thick-bedded, coarsely pelletal andoolitic.

25_ ________ Mudstone: soft, brownish-gray (10 YR3/1), thin-bedded. Separated frombed Rt-24 by andesite(?) sill 3.6 ftthick.

24- ________ Mudstone: medium-hard, grayish-brown (WYR 4/2), thin-bedded.

23_ ________ Phosphorite : cherty, hard, light-brownish-gray (ioyfi'5/l), thick-bedded,very coarsely oolitic.

Tosi Chert Member of Phosphoria Formation, lower part:

To-22___ ______ Chert: hard, brownish-black (10 YR2/1), thick-bedded.

21 _________ Phosphorite: medium-hard, brownish-gray (10 YR 4/1), thick-bedded,medium pelletal; contains phosphaticskeletal fragments.

Lower Tongue of Shedhorn Sandstone: Ls-20_ _-_____- Sandstone: pebbly, hard, light-brown

ish-gray (10 YR 5/1), thick-bedded,fine-grained; chert pebbles are asmuch as 25 mm in diameter; containsphosphatic skeletal fragments; gradesfrom bed below.

19____-____ Sandstone : hard, light-brownish-gray(10 YR 6/1), thick-bedded; containscolumnar bodies of sandstone thatcut across bedding.

18_________ - Chert: hard, dark-gray (N 4), thick-bedded.

17 _________ Sandstone: hard, medium-gray (AT" 6),thick-bedded, fine-grained.



PsOs insoluble eV U

1.6 22.3 __________ ______ ______ ______

.4 22. 7 JAP-5568 16. 6 52. 5 0. 003

23. 4

23. 9

3. 0 26. 9

.5 27. 4

7. 2 34. 6

2. 0 36. &\

.5 37. 13. 0 40. 11

5. 5 45. 6

.6 46. 2

1. 7 47. 9

.6 48. 5

.7 49. 2

7. 6 56. 8

.3 57. 1

.4 57. 5

4. 9 62. 4

1. 0 63. 4

.4 63. 8

5567 18. 3 47. 3 .003

5566 18. 6 45. 5 . 004

5540 1. 1 68. 06 . 001

5539 2.2 74.3 .002 _______

5538 25. 8 30. 26 . 006 0. 005

5537 1.8 71.06 .003 _______

5536 2. 2 70. 0 . 002

5535 26. 2 29. 5 . 007

5534 30. 5 11. 9 . 010 . 007


South Boulder Creek, Mont., lot 1365 Continued


Ls-16_

15.

14.

13.

12.

11.

10.

Q-l.

Bed Description

Lower Tongue of Shedhorn Sandstone Continued

________ Chert: hard, brownish-gray (1QYR 3/1), thick-bedded.

________ Sandstone: cherty, hard, medium-gray(N 6), fine-grained.

________ Chert: hard, brownish-gray (10 YR 3/1), thick-bedded.

_______ Sandstone: medium-hard, pale-brown(10 YR 5/3), thick-bedded, fine grained.

________ Chert: hard, brownish-gray (10 YR 3/1), thick-bedded; grades from bed below.

________ Sandstone: pebbly, hard, light-yellow ish-brown (10 YR 6/4), thick-bedded, fine-grained; chert and dolomite peb bles are as much as 75 mm in diam eter; grades from bed below.

________ Sandstone: hard, very pale brown(IOYR 7/2), thick-bedded, fine grained; crossbedded in part.

________ Sandstone: pebbly, medium-hard, pale- brown (10 YR 6/2), thick-bedded, medium-grained; chert and dolomite pebbles are as much as 70 mm in diameter; irregular contact with bed below.

Park City Formation; Franson and Gran deur Members not differentiated:

________ Dolomite: Sandy, medium-hard, light- brownish-gray (10F.R 5/1), very thick bedded.

________ Sandstone: pebbly, medium-hard,weak-yellowish-orange (10F.R 7/6), very thick bedded, medium-grained; chert and dolomite pebbles are as much as 50 mm in diameter.

._ _ ____ Dolomite: medium-hard, yellowish- gray (1QYR 7/1), thick-bedded, aphanitic; contains chert nodules.

_______ Sandstone: dolomitic, pebbly, medium- hard, weak-yellowish-orange (10 YR 7/6), very thick bedded, fine-grained; chert and dolomite pebbles are as much as 50 mm in diameter; grades from bed below.

________ Dolomite and sandstone, interbedded:medium-hard yellowish-gray (10 YR 8/1) thick-bedded aphanitic dolomite interbedded with medium-hand weak- yellowish-orange (2.5F 7/4) fine grained sandstone; sandstone consti tutes 50 to 75 percent of unit.

. -_____ Sandstone: hard, yellowish-white (2.5 Y 9/2), very thick bedded, fine-grained.

________ Dolomite: silty, hard, light-brownish- gray (10 YR 6/1), thick-bedded, aphanitic.

Quadrant Formation:________ Sandstone: hard, yellowish-white (2.5 Y

9/2), thick-bedded, fine-grained. Thickness unknown.

1 Location of contact with underlying Permian beds not certain.


(feet) (feet)

0. 6 64. 4

.8 65. 2

2. 3 67. 5

.3 67. 8

.3 68. 1

1. 0 69. 1

Uranium

SampleAcid


eV IT

4. 0 73. 1

1. 0 74. 1

2. 0 76. 1

1. 3 77. 4

1. 6 79. 0

1. 6 80. 6

15. 0 95. 6

2. 0 97. 6

7. 0 104. 6


La Marche Gulch, Mont., lot 1366

[Phosphoria Formation exclusive of Tosi Chert Member and Park City Formation measured in hand trench and natural exposure near La Marche Gulch on west side of Big Hole River in sec. 32, T. 1 S., R. 9 W., Beaverhead County, Mont. Beds strike N. 40° W. and dip 45° SW. Measured by R. F. Gosman and sampled by J. A. Peterson, in August 1951. Analyzed for uranium by U.S. Geol. Survey and for other constituents by U.S. Bur. of Mines. LOI, loss on ignition]


Bed

Rt-49.

48.

47.

46.

45.

44.

43.

42.

40-

39_

38_

37_

36.

35.

34.

33.

Description

Retort Phosphatic Shale Member of Phosphoria Formation:

Phosphorite: medium-hard, dark gray (-/V4), thick-bedded, nodular; chert y in places; apatite nodules or pebbles are as much as 30 mm in diam eter; irregular contact with bed below.

Mudstone: soft, medium-gray(N 5), thin-bedded.

Dolomite: medium-hard, light- brownish-gray (10F.R 5/1), thick-bedded; contains some apatite nodules as much as 25 mm in diameter and fine apatite pellets; PzO5 analysis may be too low.

Phosphorite: muddy, medium- hard, medium-gray (AT 5), thick-bedded, finely pelletal.

Mudstone: soft, light-yellowish- brown (10 YR 6/4).

Phosphorite: soft, dark-gray (-W3), thick-bedded, medium- pelletal; contains a few apatite nodules as much as 5 mm in diameter.

Mudstone: carbonatic(?), soft,light-gray (N 7).

Phosphorite: medium-hard, black (N2), thick-bedded, medium-pelletal; zone in mid dle of bed contains consider able amounts of calcite cement.

Dolomite: muddy, medium-hard, dark-gray (A7 3), thick-bedded, very finely granular.

Phosphorite: muddy, medium- hard, dark-gray (N 4), thick- bedded, medium-pelletal; bed is sheared.

Phosphorite: muddy, light-gray (N 7), thin-bedded, medium- pelletal; contains a few apatite nodules as much as 18 mm in diameter; bed is sheared.

Phosphorite: muddy, soft, light- gray (N 7), thin-bedded, finely pelletal.

Phosphorite: muddy, soft, thin- bedded; bed may be faulted.

Phosphorite: medium-hard, moderate-yellowish-brown (10 YR 5/6), thin-bedded, finely pelletal; contains a few apatite nodules.

Mudstone: medium-hard, moderate-yellowish-brown (10F.R 4/4); grades from bed below.

Phosphorite: muddy, medium- hard, moderate-yellowish- brown (10 YR 4/4), thick- bedded finely pelletal.

Dolomite: muddy, medium-hard, medium-gray (JV 6), very thick bedded, aphanitic.

Thick ness ffeef)

0 K

. 4

1. 0

. 2

1.3

1 9

1. 5

live thickness

(feet)

n f»

q

1 Q

O K

2.7'

4. 0

K 0

6. 7}

Uranium

Radio- Acid metric Chemical

Sample PsOs insoluble AhOa FezOs LOI eV U

RFG-5585 28.4 13.4 ____ ____ ----- 0.009 0.007

5584 3.9 68.3 ____ ____ ----- .002 _____

5583 4.3 17.7 ____ ____ ----- .004 _____

5582 22.4 12.1 1.49 2.19 14.02 .003 _____

5581 27. 0 22. 2 4. 24 2. 60 4. 18 . 006 . 005

5580 .9 73.1 2.93 1.38 5.27 .003 _____

1. 2

4.0

1.3

7.3

8. 5

3.0 11.5

2. 7 14. 2

18. 2

19. 5

6 20. 1

20. 3

1. 1 21. 4

5579 24. 0 2. 9 2. 26 1. 12 17. 63 . 006 . 004

5578 22. 8 27. 8 13. 6 2. 72 5. 44

5577 18. 7 37. 7 7. 02 3. 15 6. 94

5576 18. 7 37. 7 7. 02 3. 15 6. 94

5575 22. 7 31. 0 5. 72 2. 83 5. 7

5574 15. 4 44. 4

008

008

008

006

007

007

007 . 009

003

5573 .001


La Marche Gulch, Mont., lot 1366 ContinuedChemical analyses (percent)

Bed Description

Retort Phosphatic Shale Member ofPhosphoria Formation Con.

Rt-32. _____ M udstone: soft, light-yellowish- brown (10 YR 6/4), thin- bedded.

31____- Mudstone: phosphatic, medium- hard, grayish-brown (10 YR 4/2), thin-bedded; apatite is finely pelletal.

30____- Phosphorite: muddy, medium- hard, medium-gray (N 6), thin-bedded, finely pelletal.

29--__- Phosphorite and mudstone, interbedded: soft light-gray (N 7) thin-bedded finely pelletal muddy phosphorite interbedded with soft medium-gray (./V 6) thin-bedded phosphatic mudstone.

28_-__- Mudstone: phosphatic(?), soft,fissile.

27.---- Phosphorite: muddy(?), medi um-hard, thin-bedded, pelle tal.

26_ _ _ _ _ Mudstone: phosphatic, medium- hard, black (N 2), thin- bedded; apatite is finely pel letal.

25---... Phosphorite: muddy, medium- hard, light-brownish-gray (10 YR 6/1), thick-bedded, medium-pelletal and skeletal.

Park City Formation; Franson and Grandeur Members not differen tiated :

Pc-24__-_-- Dolomite: medium-hard, light- gray (./V 7), thick-bedded, skeletal; contains a bed of chert 1.0 ft thick 4.0 ft above base of unit. Fossil-coll. No. 12696.

23 ______ Sandstone: carbonatic, medium- hard, thick-bedded.

22______ Dolomite: medium-hard, dark- gray (N 4), very thick bed ded, aphanitic.

21______ Siltstone: hard, light-brown(7.5 YR 5,6), thin-bedded.

20___-_- Dolomite: medium-hard, verythick bedded.

19__---_ Dolomite: medium-hard, medi um-gray (N6), thick-bedded, aphanitic; contains mudstone parting 0.2 ft thick at top.

18_---_- Dolomite: silty, medium-hard, medium-gray (Af 6), very thick bedded, aphanitic; contains light-brownish-gray (10 YR 5/1); mudstone partings 0.3 ft thick at top and base of unit.

17_-___- Dolomite: medium-hard, medi um-gray (./V 6), very thick bedded, aphanitic.

Cumula- Thick- five ness thickness (feet) (feet) Sample

0. 1 21. 51

Uranium

Acid insoluble Fe2 O3 LOT


eU U

6 22. 1

22. 5

3. 3 25. 8

26.0

26. 2

26.4

26. 8

13. 0 39. 8

4. 1 44. 7

1. 0 45. 7

9. 3 55. 0

11. 0 66. 0

4. 2 70. 2

7. 5 77. 7

RFG-5572 15.8 44.7 ____ ____ ----- 0.004

5571 16. 7 43. 8 . 006 0. 004

5570 13. 4 50. 7 .004


La Marche Gulch, Mont., lot 1366 ContinuedChemical analyses (percent)

Bed

Pc-16.

15.

14.

13.

12.

11.

10.

Q-2.

1.

Description

Park City Formation; Franson and Grandeur Members not differen tiated Continued

Dolomite: medium-hard, light- brownish-gray (WYR 6/1), very thich bedded: contains numerous lenses of sandstone as much as 0.3 ft thick and many dark-gray (N 4) chert nodules and lenses as much as 2.0 ft thick; becomes less cherty toward top of unit.

Siltstone: dolomitic, hard, light- yellowish-brown (WYR 6/4), very thick bedded.

Chert: hard, pale-brown (WYR 5/2), very thick bedded; grades from bed below.

Sandstone: hard, light-yellowish- brown (WYR 6/4), very thick bedded, very fine grained.

Dolomite: cherty, medium-hard, light-brownish-gray (10 YR 6/1), very thick bedded, apha nitic; much of chert occurs as sponge spicules.

Sandstone: dolomitic, hard, pale- brown (2.5 Y 5/2), thick- bedded, very fine grained.

Dolomite: cherty, medium-hard, aphanitic; bedding is indis tinct; grades from bed below.

Dolomite: medium-hard, light- gray (N7), very thick bedded aphanitic: contains many round to eliptical nodules of light-yellowish-brown (10 YR 6/4) chert; grades from bed below.

Sandstone: hard, pale-brown (WYR 6/2), very thick bedded, fine-grained; con tains a few chert and dolo mite pebbles as much as 45 mm in diameter, most of which are concentrated near the base; grades from bed below.

Dolomite: medium-hard, medi um-gray (N 5), thick-bedded, aphanitic; contains several lenses of very fine grained sandstone.

Siltstone: hard, light-yellowish- brown (WYR 6/4), thin- bedded.

Dolomite: hard, medium-gray (N 5), thick-bedded, apha nitic.

Sandstone: hard, light-gray (N 7), very thick bedded, fine grained.

Dolomite: sandy, muddy, hard, medium-gray (N 7), very thick bedded, aphanitic; sand is very fine.

Quadrant Formation, upper part:Sandstone: hard, light-brown

ish-gray (WYR 5/1), thick- bedded, fine-grained.

Sandstone: hard, dark-gray (N 4), very thick bedded, fine grained.

Cumula- Thick- tiae ness thickness (feet) (feet)

18. 0 95. 7

Uranium

SampleAcid

insoluble AljOs Fe203 LOI


eU U

3. 0 98. 7

2. 2 100. 9

1. 0 101. 9

3. 0 104. 9

6. 5 111. 4

18. 0 129. 4

14. 6 144. 0

2. 0 146. 0

5. 5 151. 5

. 8 152. 3

7. 2 159. 5

4. 0 163. 5

7. 8 171. 3

5. 0 176. 3

3. 0 179. 3


Logan, Mont., lot 1367

[Permian rocks measured along ridge on east side of road about 1 mile northwest of Logan, sec. 26, T. 2 N., R. 2 E., Gallatin County, Mont. Beds strike N. 70° E. and dip 20° N. Measured by R. W. Swanson and J. A. Peterson and sampled by Swanson, in September 1951. Analyzed for PjOs and acid insoluble by U.S. Bur. of Mines, and for uranium by U.S. Qeol. Survey]


Bed

Us-34.

33-

32,

31.

To-30-

29.

28.

27.

26.

25.

24-

23-

22.

21-

20-

19-



Upper tongue of Shedhorn Sandstone: 1Sandstone: hard, very-pale-brown (10F.R 7/2), 17.0 17.0

fine-grained; contains sandstone columns (?); thickness is approximate, and only about two- thirds of unit is exposed in outcrop.

Sandstone: hard, fine-grained, yellowish-gray 4. 6 21. 6 (WYR 7/1) to pale-brown (WYR 5/2), thick- bedded; contains flat dolomite pebbles in lower 1.5 ft; irregular contact with bed below.

Sandstone: hard, yellowish-gray (WYR 7/1), 13. 2 34. 8 very thick bedded, fine-grained; contains black dolomite pebbles in beds 0.1 feet thick; crossbedded in part.

Sandstone: hard, very pale brown (WYR 7/2), 6. 0 40. 8 fine-grained; crossbedded in 1-ft layers; irregu lar contact with bed below; contains scattered dolomite pebbles.

Tosi Chert Member of Phosphoria Formation:Chert: dolomitic, hard, light-brownish-gray 2. 0 42. 8

(WYR 6/1); dolomite is irregularly dis tributed.

Sandstone: carbonatic, hard, very pale brown .5 43. 3 (WYR 7/2), very fine grained; undulant con tact with bed below.

Chert: hard, pale-brown (WYR 6/2), thin- 1. 7 45. 0 bedded; contains some mudstone partings.

Dolomite: muddy, soft, very pale brown (WYR . 3 45. 3 7/2), aphanitic; undulant contact with bed below.

Chert: sandy, hard, light-brownish-gray (WYR .4 45. 7 6/1)., thin-bedded; contains phosphatic skeletal fragments.

Chert: hard, pale-brown (WYR 6/2), thin- .6 46. 3 bedded; contains some sandy laminae.

Chert: dolomitic, hard, light-brownish-grav .9 47. 2 (10 YR 5/1), thin-bedded.

Mudstone and chert, interbedd.ed: soft yellowish- gray (2.5F 8/2) thin-bedded carbonatic mudstone interbedded with hard very pale brown (WYR 7/2) thin-bedded chert; chert constitutes 40 percent of unit.

Chert and limestone, interbedded: hard very 1. 9 pale brown (10 YR 7/2) thin-bedded chert interbedded with soft yellowish-gray (2.5F 7/2) thin-bedded muddy limestone.

Mudstone: soft, yellowish-gray (2.5 Y 7/2), . 7 thin-bedded.

Chert: hard, very pale brown (WYR 7/2), thin- 1. 0 bedded; irregular contact with bed below.

Chert: sandy, hard, pale-brown (WYR 6/2), 1.2 very thick bedded; sand is fine; contains glauconite.

Sample

Uranium

Acid Radio- insoluble metric eU

1. 5 48. 7 RWS-5593

50. 6

51. 3

52. 3

53. 5"

5592

5591

1. 4 72. 7 0. 001

.9 68. 8 . 000

1. 3 62. 4 . 001



Logan, Mont., lot 1367 Continued

To-18-

17-

15-

13-

12-

11.

10.

Bed Description

Tosi Chert Member of Phosphoria Formation Con. .___ Chert: hard, pale-brown (IOYR 6/2), thin-

bedded; contains columnar bodies 0.1 ft in diameter of fine-grained cherty sandstone in uppermost 2 ft.

____ Sandstone: phosphatic, hard, pale-brown (IOYR5/3), thick-bedded, fine-grained; apatite in skeletal and medium-pelletal; contains glau conite.

____ Dolomite: sandy, hard, thick-bedded, aphanitic;sand is very fine; contains glauconite; grades from bed below; contains scattered lenses and columnar bodies of dolomitic sandstone.

____ Chert: hard, light-brownish-gray (IOYR 6/1),thin-bedded; contains glauconite.

_ _. _ Chert: hard, thin-bedded; contains glauconite- _ _ ____ Mudstone: sandy, carbonatic, soft, weak-

yellowish-orange (2.5F 8/4), thin-bedded; sand is fine.

____ Dolomite: muddy, medium-hard, weak-yellow ish-orange (2.5F 8/4), thick-bedded, aphanitic.

____ Dolomite: sandy, soft, weak-yellowish-orange(2.5F 8/4), thin-bedded, aphanitic; sand is very fine.

____ Carbonate rock: muddy, medium-hard, weak- yellowish-orange (2.5F 8/4), thin-bedded.

9__________ Dolomite: sandy, hard, pale-brown (IOYR 5/2),thick-bedded, aphanitic; sand is very fine; contains glauconite; grades from bed below.

8 __--_-_- Chert: sandy, hard, pale-brown (IOYR 6/2), thin-bedded; contains glauconite; composi tion of bed is variable, ranging from chert to cherty sandstone; grades from bed below. Fossil colln. No. 12699.

7__________ Chert: hard, pale-brown (IOYR 6/2), thin- bedded; contains phosphatic skeletal frag ments, glauconite, and a few scattered quartzite pebbles; irregular contact with bed below.

Lower Tongue of Shedhorn Sandstone: Ls-6_ _________ Sandstone: dolomitic, hard, very pale brown

(IOYR 7/2), very thick bedded, very fine grained; irregular contact with bed below.

Quadrant Formation, upper part: Q-5________.__ Sandstone: hard, yellowish-white (IOYR 9/1),

very thick bedded, fine-grained. 4_ __________ Dolomite: medium-hard, light-brownish-gray

(10 YR 6/1), very thick bedded, aphanitic; contains stringers of fine-grained sandstone.

3___________ Sandstone: hard, white (N 9), very thick bedded,fine-grained, crossbedded in basal 1 ft.

2___________ Dolomite: sandy, hard, light-yellowish-brown(IOYR 6/4); sand is fine; contains a few dolo mite pebbles.

1_ __________ Sandstone: hard, white (N 9), very thick bedded,fine grained.

1 Contact with overlying conglomerate of Ellis Group approximately located.


(feet) (feet)

5. 8 59. 3


Uranium

1. 1

1. 1

.7

1. 0

60. 4

61. 5

1. 6 63. 1

.9 64. 01. 1 65. 1

65. 8

66. 9

1. 3 68. 1

1. 5 69. 6

1. 8 71. 4

.6 72. 0

2. 9 74. 9

9. 3 84. 2

2. 0 86. 2

4. 4 90. 6

2. 2 92. 8

6. 0 98. 8

Sample P.OsAcid

insolubleRadio-

metric eU

709-931 O-64 19


Hawley Creek, Idaho, lot 1454

Phosphoria Formation and upper part of Park City Formation measured on north side of Hawley Creek, NE}4 sec. 36, and lower part of Park City Formation measured on divide west of Deer Creek, SEH sec. 25, T. 16 N., B. 27 E., Lemhi County, Idaho. Beds above unit Pc-29 strike N. 28° W. and dip 75° W.; beds below unit Pc-29 strike N. 50°-75° W. and dip 15°-25° 8. Thickness of beds below unit Pc-29 is approximate because of poor exposures. Measured by E. K. Cressman in August, 1954]

Thickness Cumulative Bed Description (feet) thickness (feet)

Tosi Chert Tongue of Phosphoria Formation: To-43.------------------ Chert: hard, dark-gray, granular-appearing; weathers moderate yellow. 0. 5 0. 5

Overlain by dark-gray calcareous mudstone of Dinwoody(?) formation. 42--.---------------- Chert: hard, dark-gray, granular-appearing._________________________ 1. 2 1. 741_____-__----_-__--- Mudstone: dark-gray to brownish-gray, thin-bedded to fissile__________ 4.0 5.740------------------- Chert: dark-gray, very thick bedded__..________--__-_-__-____-______ 112.0 117.739___________-_--__-- Chert: dark-gray, very thick bedded; contains irregular nodules of 2. 6 120. 3

medium-gray fine-grained carbonate rock. 38 __ _--__--_----__ Chert: dark-gray, very thick bedded______________________________ 17.0 137.337_------------------ Chert: black, thin-bedded__-__-__-------_-------------_---------_- 7.8 145.136--_-_-__--_-------_ Dolomite: medium-gray to brownish-gray, fissile; contains a few apatite . 7 145. 8

pellets. -35------------------- Chert: black, thin-bedded; pitchy luster___-___---_-___-___________ 1.0 146.8(34)__-_____________ Covered___________________________-----_______-__-____.__ 78. 0 224. 8

Retort Phosphatic Shale Tongue of Phosphoria Formation: Rt-33________-__-_-__-__ Phosphorite: dark-gray, finely to coarsely oolitic._-___-__-__-_-_.-___ .4 225. 2

Park City Formation: Pc-32.__________________ Dolomite and chert: sandy hard medium-gray very thick bedded dolomite 2. 5 227. 7

that contains black chert nodules and masses that constitute half of bed. 31.________-___ ____ Dolomite: sandy, hard, medium-gray, very thick bedded._____________ 7.0 234.730______--___---_--._ Dolomite: sandy, weak-yellowish-orange, platy_____________________ 16. 0 250. 729._--_-----_------__ Sandstone: medium-gray, thick-bedded, very fine grained; slightly 3.0 253.7

dolomitic. (28)-_____--___-._ Covered..._______________________.___-_______-_______ 24. 4 278. 127.____..----_-__----_ Dolomite and chert: sandy dark-gray aphanitic dolomite passing laterally 4. 3 282. 4

and vertically into black chert. (26)-__ .-____-__-__ Covered..-___________________________________________ 8.0 290.425-____---__----- Similar to bed Pc-27__________________________________ 5. 5 295. 924_ _____-____-__-_-__ Dolomite: sandy (?), dark-gray, thick-bedded, aphanitic- ______________ 6. 6 302. 523-__ ___-____-__--___ Sandstone: Dolomitic, medium-light-gray, very fine grained-__________ 9.0 311.522___________-__--___ Dolomite: light-gray, thin-bedded, aphanitic___--____-_--_--_-__-_- 9.0 320.5(21).________-___--__ Covered__________________-_-_.-______-_____-__._______.__ 18. 0 338. 520---___----_--_----- Chert: medium-gray, thick-bedded. ________________________________ 26.0 364.519___________________ Dolomite: medium-gray, thick-bedded, very fine grained to aphanitic; 25.0 389.5

contains a few medium-gray chert nodules. (18)-_._______________ Covered_____________________________________________________ 35. 0 424. 517. _____-__---___--__ Dolomite: light-gray, thin- to thick-bedded, very fine grained to aphanitic; 65. 0 489. 5

contains 25 percent medium-gray chert nodules. 16__ _________--_--___ Sandstone: calcareous, yellowish-gray to light-gray, very fine grained; 16.0 505.5

laminated in part. (15)-_-__.-______- Covered-____________________________________________________ 133. 0 638. 514_______________.___ Chert: medium-gray____--___-_----__-_----_--_-------_--_----_-_- 5.0 643.5

(13)-________-_-___. Covered: dolomite float-____-____-_--_______-__-__-_-__-_-____--__ 18.0 661.5(12)_._______________ Covered: dolomite and chert float---_--_-__-_-_--_-----_--___-_____ 6.0 667.511.__________________ Dolomite: light-gray, thin- to thick-bedded, very fine grained..________ 85. 0 752. 5

(10)________________ Covered: dolomite and chert float___--____-_--_______-_____________ 26.0 778.59,__________________ Dolomite: light-gray thin- to thick-bedded, very fine grained to aphanitic; 12. 0 790. 5

contains 10 percent medium-gray fossiliferous chert nodules. 8_ __________________ Dolomite: light-gray, thin- to thick-bedded, very fine grained to aphanitic. 18. 0 808. 57-___._________-____ Chert: medium-gray____________________-_-_-__._______--_____ 6.0 814.56.__________________ Dolomite: light-gray, thin- to thick-bedded, very fine grained to aphanitic_ 15. 0 829. 55---__-___-________- Chert: light-gray, thick-bedded_-____-_--__-_-_-_-_---_--__-_______ 3.0 832.54.__________________ Dolomite: light-gray, thin- to thick-bedded, very fine grained to aphanitic_ 14. 0 846. 5(3)_._______________ Covered: dolomite and chert float-__--___-_--______-__-__-_________ 7.0 853.52___________________ Chert: medium-gray-________--___---___-_____-_-_________-_______ 1.0 854.5l-_-________________ Dolomite: light-gray, thin- to thick-bedded, very fine grained; underlain 2. 0 856. 5

by sandstone (Quadrant Formation?).


Pulpit Rock, Mont., lot 1479[Shedhorn Sandstone and Phosphoria Formation measured in NEJ4NEH sec. 3, T. 9 S., R. 4 E., Gallatin County, Mont., on west side of Qallatin River about

500 ft above Pulpit Rock by R. W. Swanson, assisted by W. B. Hall, in August 1956. Beds strike about N. 45° W. and dip 10° N W. Analyzed by U.S. Qeol. Survey]

Chemical Analyses (percent)

Acid PzOs insolubleBed

D-36.

(35). Us-34..

33.

32-

31.

30.

29.

28.

27.

26_.

25..

(24). 23_.

(22).

To-20.

19.

Rt-18-

17.

16.

15.

14.

13.

Description

Dinwoody Formation, basal part not measured:Mostly covered: scattered small outcrops and much

float of typical brown-weathering limestone of the Dinwoody.

Upper member of Shedhorn Sandstone:Covered: includes Shedhorn-Dinwoody contactSandstone: hard, massive, fine-grained, light-brown

ish-gray (10 YR 6/1); contains much nodular chert in top 0.3 ft.

Chert and sandstone, interbedded: hard fine-grained brownish-gray (10 YR 4/1) sandstone thinly interbedded with light-brownish-gray (10 YR 6/1) chert.

Chert: hard, thin- and somewhat wavy bedded, light- brownish-gray (IQYR 6/1).

Sandstone: hard, massive, fine-grained, brownish- gray (10 YR 4/1); contains thin beds of chert in upper and lower parts.

Chert: hard, thin- and wavy bedded, light-brownish- gray (10Y.fi; 6/1); contains some interbedded sand stone in upper part.

Chert and sandstone: hard, thick-bedded to massive; sandstone and chert irregularly distributed.

Chert: hard, thin- and wavy bedded, light-brownish- gray (10 YR 6/1); contains thin irregular layers of sandstone.

Sandstone: hard, massive, fine-grained, brownish- gray (10 YR 4/1); contains lenses and irregular layers of chert in upper part.

Chert: hard, laminated to thin-bedded, light-brown ish-gray (10 YR 6/1).

Sandstone: hard, fine-grained, light-brownish-gray (10F.R 6/1); contains numerous small chert nodules.

Covered.._ ____________-_-_-___-_-_-_---____-__Sandstone: hard, massive, fine-grained, light-brown

ish-gray (10 YR 6/1); contains irregular masses of chert.

Covered._ _____________________________________Sandstone: hard, thick-bedded to massive, fine

grained, light-brownish-gray (10 FB 6/1). Tosi Chert Tongue of Phosphoria Formation:

Chert: hard, poorly bedded, brownish-gray (10F.R 4/1); locally sandy.

Covered: probably chiefly thin-bedded chert _______Retort Phosphatic Shale Tongue of Phosphoria Forma

tion:Mudstone: medium-hard, laminated to fissile,

grayish-brown (WYR 4/2) to pale-brown (1QYR 6/3).

Phosphorite: hard- to medium-hard, thick-bedded, finely to coarsely pelletal, grayish- to pale-brown (10FE 4/2 to 6/2); contains purple and white fluorite, quartz grains, and quartz veinlets.

Phosphorite: medium-hard, poorly bedded, medium- to coarsely pelletal, brownish-gray (10 YE 3/1); contains phosphatic shell fragements and purple and white fluorite.

Phosphorite: medium-hard, thick-bedded, finely to very coarsely pelletal, brownish-gray (10 YR 4/1); contains quartz sand.

Mudstone: soft, fissile, dusky-brown (IQYR 3/2); contains apatite pellets.

Sandstone: hard fine-grained pale-brown (lOFfi 6/2) sandstone containing locally many pebbles of chert to \% in. diameter and pellets, shell fragments, and sandy nodules.



1. 05.8

1.0 6.8

3. 5 10. 3

2. 3 12. 6

5. 0 17. 6

4. 2 21. 8

9. 2 31. 0

2. 5 33. 5

7. 6 41. 1

.9 42. 0

1. 0 43. 0

2. 0 45. 010. 5 55. 5

8. 5 64. 05. 0 69. 0

12.5 81.5 __--__ -

14.5 96.0 -.____--_- ------

1.0 97.0 --__----_. ------

1. 0 98. 0 RWS-7544 25. 9

.8 98. 8

.5 99. 3

.2 99. 5

. 6 100. 1

7543 27. 2

7542 13. 5

27.5

20. 0

33.5


Pulpit Rock, Mont., lot 1479 Continued

Bed

(12). Ls-11-

(10).

(7).

(5)-

(2).

Q-l.

Description

Lower member of Shedhorn Sandstone:Covered-______________________________________Sandstone: medium-hard, poorly bedded, fine

grained, light-brownish-gray (10 YR 6/1).Covered.______________________________________Sandstone: hard, medium- to thick-bedded, medium-

grained, pale-brown (10 YR 6/2); cherty 1 ft above base and chert nodules are found higher.

Sandstone and chert: hard thin- to medium-bedded medium-grained light-brownish-gray (10 YR 6/1) sandstone containing thin interbeds and some nodules of chert.

Covered-______________________________________Sandstone: calcareous, hard, thin- to thick-bedded,

coarse- to very coarse grained; locally contains pebbles of carbonate rock; very pale brown (10 YR 7/2); contains many dark grains and fossil fragments (bryozoa, gastropods, sponge spieules).

Covered.______________________________________Sandstone: hard, thin- to thick-bedded, fine-grained,

light-brownish-gray to pale-brown (10 YR 6/1 to 2.5F 6/2); contains many drak grains and local carbonate lenses and flat pebbles.

Chert and sandstone, interbedded: hard fine-grained pale-brown (10 YR 6/2) sandstone containing numerous apatite grains interbedded with hard thin-bedded light-brownish-gray (10 YR 6/1) chert containing dolomite rhombs, sponge spieules, and locallv, much very fine quartz sand; at base, contains chert and carbonate pebbles as much as 1 in. diameter.

Covered interval: dug out calcareous medium-hard fine- to very coarse-grained grayish-orange (10 YR 7/4) sandstone 7 ft above base and silty to very finely sandy medium-hard weak-vellowish-orange (10 YR 7/6) to grayish-orange (10 YR 7/4) car bonate rock at 9}£, 18%, and 22 ft above base.

Quadrant Formation, top bed:Sandstone: hard massive, medium-grained- yellowish-

white (10 YR 9/1). Forms extensive bluffs.


(feet) (feet)

0. 9 1. 6

3. 0 3. 5

4. 3 4. 8

10. 0

101. 0102. 6

105. 6109. 1

1. 7 110.

115. 1119. 9

2. 2 122. 15. 5 127. 6

3. 5 131. 1

22. 0 153. 1

10. 0

Sample

Chemical Analyses (percent)

Acid PiOs insoluble


Wigwam Creek, Mont., lot 1481

[Permian rocks measured in reconnaissance from natural exposures on north side of Wigwam Creek Canyon in SEJ4 sec. 33 and NWJ4 sec. 4, T. 7 and 8 S., K. 2 W., MadisonCounty, Mont., in July 1966, by R. W. Swanson. Beds strike NE and dip 10-15° NW]



Din woody Formation, basal bed: D-27__________________ Carbonate rock: medium-hard, thin-bedded, dense, pale-brown_____________ 3. 0 3. 0

Upper member of Shedhorn Sandstone: Us-26_______-___________ Sandstone: hard, thin-bedded, fine-grained, pale-brown (IQYR 5/2) to light- 8. 0 8. 0

brown (7.5YR 6/4); contains lenses of sandy chert. 25___________________ Sandstone: calcareous, medium-hard, fine-grained, poorly bedded, yellowish- 9. 0 17. 0

gray (2.5F 7/2); not well exposed; contains shell fragments; basal contact irregular.

24____---__-___-_-__- Sandstone: hard, thin- to thick-bedded, fine-grained, brownish-gray (IQYR 2. 0 19. 04/1).

Tosi Chert Tongue of Phosphoria Formation: To-23__...__._.__-____ Chert: hard, thin- to thick-bedded, pale-brown (IQYR 6/2) to light-yellowish- 12. 0 31. 0

brown (IQYR 6/4); locally sandy, lower part thinner bedded; fissile silty interbeds are common; contains columnar sandstone concretions.

Lower tongue of Shedhorn Sandstone: Ls-22_____-_-_-_-_-_-___ Sandstone: phosphatic, hard, poorly bedded, fine-grained and locally gritty in 1. 8 32. 8

lower half, pale-brown (2.5F 6/2); cherty at top; contains shell fragments and teeth; basal contact coarsely irregular.

21 _________-_-_-_-___ Sandstone: hard, very fine to medium-grained, pale-brown (10 YR 6/2); basal .8 33.6contact irregular to undulating.

20_ ___________________ Chert and sandstone: nodular to massive sandy pale-brown (IQYR 6/2) chert 5. 8 39. 4(70 percent) containing irregular patches and lenses of fine-grained light- yellowish-brown sandstone; basal contact irregular.

19._----------------_ Sandstone: cherty, hard, fine-grained, massive, pale-brown (7.5YR 6/2); very 6. 0 45. 4cherty in top 1^_ ft; scattered chert found below; gradational basal contact.

18____-------------__ Sandstone: cherty, hard, very fine to fine-grained, thick-bedded to massive, 40. 5 85.9light-yellowish-brown (IQYR 6/4); light-brownish-gray (10F.R 6/1) chert very irregularly distributed throughout bed.

(17)__________________ Covered__________________________-_-_-_--_--_-_-_-___-_-_-_---_--__- 26. 0 111. 916_ __________________ Sandstone: hard, fine-grained, somewhat cherty; contains apatite pellets. ___ 6.0 117.9

(15)---------_-------- Covered__-_-_-_-__-___-_-_-_----_____--__-_-----_---_----------_-_-_ 2. 0 119. 914__-_---_-_-_---___- Chert: sandy, thick-bedded, very pale orange (IQYR 9/2); contains sponge 3.0 122.9

spieules; sand very fine. (13)_________________ Covered: possibly carbonate rock____-___-___________-_-_-_-_.________ 13.0 135.9

12_ ___-_____-_-___-__ Chert: sandy, like bed Ls-14; contains abundant siliceous sponge spicules___ 2. 0 137. 911-_--____-_---_-_-_- Sandstone: calcareous, medium-hard, fine-grained, reddish-brown; contains .5 138.4

shell fragments and apatite pellets. 10_ __________________ Carbonate rock: sandy, hard, aphanitic, light-gray; contains brachiopod 1.5 139.9

shells. (9).-._--._.-._.-.-.-. Covered ------_.-...-__._._._.---_-.-.----_-_._._.-.-.---.-_---._- . 5 140. 48---____-_-___--_--_- Sandstone: carbonatic, very fine to medium-grained, pale-brown (7.5 YR 6/2) __ .5 140.97--_-_-----_-_-_--__- Chert: sandy ____________________._._._._._.___._-_._._._._._._._._. 1.0 141.96_ ___________________ Sandstone: carbonatic to cherty, hard, fine-grained, light-brownish-gray 1.0 142.9

(10F.R 6/1); containa abundant siliceous sponge spieules and nvimerous apatite pellets.

5_-__-_-____.________ Covered..._______________-________________--___-_-_-----______ 1. 0 143. 9Grandeur Tongue of Park City Formation:

G-4______-__-___________ Dolomite: hard, locally cherty, thick-bedded to massive, pale-brown (7.5Y.R 5. 2 149. 16/2); upper 4 ft weather hackly; forms low bluff.

3---_----__-___-_-_-_- Dolomite: hard, aphanitic, thick-bedded, very pale brown to very pale orange 11. 5 160. 6(IQYR 7/2-7.5YR 8/2); contains small round chert nodules.

2_____________________ Covered: probably mostly dolomite- ___________________________________ 19.0 179.6Quadrant Formation, top bed:

Q-l______-_-_-____-_____ Sandstone: hard, fine-to medium-grained, white.________________________ 5.0 5.0


REFERENCES CITED

Alexander, R. G., 1951, Geology of the Whitehall area Montana:Princeton Univ., Doctoral Dissert. Ser., Pub. 5125.

Altschuler, Z. S., and Oisney, B. A., 1952, X-r&y evidence ofthe nature of carbonate-apatite [abs.] : Geol. Soc. AmericaBull., v. 63, p. 1230-1231.

Altschuler, Z. S., Clarke, R. S., Jr., and Young, E. J., 1958,Geochemistry of uranium in apatite and phosphorite: U.S.Geol. Survey Prof. Paper 314-D, 45 p.

Anderson, A. L., 1930, The geology and mineral resources' ofthe region about Orofino, Idaho: Idaho Bur. Mines andGeology Pamph. 34, 63 p.

American Commission on Stratigraphic Nomenclature, 1961,Code of stratigraphic nomenclature: Am. Assoc. PetroleumGeologists Bull., v. 45, p. 645-665.

Arrhenius, Gustaf, 1952, Sediment cores from the East Pacific:Swedish Deep-Sea Exped. 1947-48 Repts., v. 5, pts. 1 and2, 227 p.

Arrhenius, Gustaf, Bramlette, M. N., and Picciotto, E. E., 1957,Localization of radioactive and stable heavy nuclides inocean sediments: Nature, v. 180, p. 85-86.

Baas Becking, L. G. M., Kaplan, I. R., and Moore, D., 1960,Limits of the natural environment in terms of pH andoxidation-reduction potentials: Jour. Geology, v. 68, p. 243-285.

Bien, G. S., Contois, D. E., and Thomas, W. H., 1958, Theremoval of soluble silica from fresh water entering thesea: Geochim. et Cosmochirn. Acta, v. 14, p. 35-54.

Blackstone, D. L., Jr., 1954, Permian rocks in Lemhi Range,Idaho: Am Assoc. Petroleum Geologists Bull., v. 38, p.923-925.

Bostwick, D. A., 1955, Stratigraphy of the Wood River forma tion, south-central Idaho: Jour. Paleontology, v. 29, p.941-951.

Bramlette, M. N., 1946, The Monterey formation of Californiaand the origin of its siliceous rocks: U.S. Geol. SurveyProf. Paper 212, 57 p.

Breger, C. L., 1911, Origin of some mineral deposits bybacteria: Mining World, v. 35, p. 289-91.

Brotherhood, G. R., and Griffiths, J. C., 1947, Mathematicalderivation of the unique frequency curve: Jour. Sed.Petrology, v. 17, p. 77-82.

Bruneau, L., Jerlov, N. G., and Koczy, F. F., 1953, Physical andchemical methods.: Swedish Deep-Sea Exped. 1947-1948Repts., v. 3, pt. 2, p. 99-112.

Burst, J. F., 1958, "Glauconite" pellets; their mineral natureand applications to stratigraphic interpretations: Am.Assoc. Petroleum Geologists Bull., v. 42, p. 310-327.

Calkins, F. C., and Enimons, W. H., 1915, Description of thePhilipsburg quadrangle, Montana: U.S. Geol. Survey Geol.Atlas, Folio 196.

Cloud, P. E., Jr., 1955, Physical limits of glauconite formation:Am. Assoc. Petroleum Geologists Bull., v. 39, p. 484-492.

Cobban, W. A., Imlay, R. W., and Reeside, J. B., Jr., 1945, Typesection of Ellis formation (Jurassic of Montana: Am.Assoc. Petroleum Geologists Bull., v. 29, p. 451-453.

Condit, D. D., 1919, Oil shale in western Montana, southeasternIdaho, and adjacent parts of Wyoming and Utah: U.S.Geol. Survey Bull. 711-B, p. 15-40.

Oondit, D. D., Finch, E. H., and Pardee, J. T., 1928, Phosphaterock in the Three Forks-Yellowstone Park region, Montana :U.S. Geol. Survey Bull. 795-G, p. 147-209.

Craig, Harmon, 1953, The geochemistry of the stable carbonisotopes: Geochim. et Cosmochim. Acta, v. 3, p. 53-92.

Cressman, E. R., 1955, Physical stratigraphy of the Phosphoria formation in southwestern Montana: U.S. Geol. Survey Bull. 1027-A, p. 1-31.

Ourrie, Ronald, 1953, Upwelling in the Benguela current: Nature, v. 171, p. 497-500.

Duncan, Helen, 1961, Corals from Permian rocks of the North ern Rocky Mountain region, in Short paper in the geologic and hydrologic sciences: U.S. Geol. Survey Prof. Paper 424-B, p. B235-B236.

Eaton, R. O., 1950, Littoral processes on sandy casts: First Conf. Coastal Eng. Proc., p. 140-154.

Emery, K. O., and Rittenberg, S. C., 1952, Early diagenesis of California basin sediments in relation to origin of oil: Am. Assoc. Petroleum Geologists Bull., v. 36, p. 735-805.

Emmons, W. H., and Calkins, F. C., 1913, Geology and ore deposits of the Philipsburg quadrangle, Montana: U.S. Geol. Survey Prof. Paper 78, 271 p.

Fairbridge, R. W., 1957, The dolomite question, in LeBlanc, R. J., and Breeding, J. G., eds., Regional aspects of car bonate deposition a symposium: Soc. Econ. Paleontol ogists and Mineralogists Special Pub., no. 5, p. 125-178.

Fedosov, M. V., 1959, The chemical basis of primary production in the sea [abs.] : Internat. Oceanog. Cong. Rept., p. 886- 891.

Fleming, R. H., and Revelle, Roger, 1939, Physical processes in the ocean, in Trask, P. D., ed., Recent marine sediments, a symposium: Tulsa, Okla., Am. Assoc. Petroluem Geol ogists, p. 48-141; reprinted as California Univ. Scripps Inst. Oceanography Contr. 70, 1939.

Folk, R. L., and Weaver, C. E., 1952, A study of the texture and composition of chert: Am. Jour. Sci., v. 250, p. 498-510.

Forsman, J. P., and Hunt, J. M., 1958, Insoluble organic matter (kerogen) in sedimentary rocks of marine origin, in Weeks, L. G., ed., Habitat of oil, a symposium: Tulsa, Okla., Am. Assoc. Petroleum Geologists, p. 747-778.

Freeman, V. L., Ruppel, E. T., and Klepper, M. R., 1958, Geology of part of the Townsend Valley, Broadwater and Jefferson Counties, Montana: U.S. Geol. Survey Bull. 1042-N, p. 481-556.

Frenzel, H. L., and Mundorff, M. J., 1942, Fusulinidae from the Phosphoria formation of Montana: Jour. Paleontology, v. 16, p. 675-684.

Gale, H. S., 1911, Rock phosphate near Melrose, Montana: U.S. Geol. Survey Bull. 470, p. 440-451.

Gilluly, James, 1937, Geology and mineral resources of the Baker quadrangle, Oregon: U.S. Geol. Survey Bull. 879, p. 21-27.

Goddard, E. N., chm., and others, 1948, Rock-color chart: Wash ington, D.C., Natl. Research Council, 6 p.

Grim, R. E., 1953, Clay mineralogy: New York, McGraw-Hill Book Co., 384 p.

Groot, J. J., 1955, Sedimentary petrology of the Cretaceous sedi ments of northern Delaware in relation to paleogeographic problems: Delaware Geol. Survey Bull. 5, 157 p.

Grout, F. F., and Balk, Robert, 1934, Internal structures of the Boulder batholith: Geol. Soc. America Bull., v. 45, p. 877-896.

Gulbrandsen, R. A., 1960a, Petrology of the Meade Peak member of the Phosphoria formation at Coal Canyon, Wyoming: U.S. Geol. Survey Bull. 1111-C, p. 71-146.

1960b, Minor elements in phosphorites of the Phosphoria formation [abs.] : Geol. Soc. America Bull., v. 71, p. 1876.


Hadding, Assar, 1932, Glauconite and glauconitic rocks, pt. 4 of The pre-Quaternary sedimentary rocks of Sweden: Lunds Geol.-Min. Inst. Medd., no. 51.

Hague, Arnold, Weed, W. H., and Iddings, J. P., 1896, Yellow- stone National Park: U.S. Geol. Survey Geol. Atlas, Folio 30.

Hague, Arnold, and others, 1899, Geology of the Yellowstone National Park: U.S. Geol. Survey Mon. 32, pt. 2, 893 p.

Harvey, H. W., 1955, The chemistry and fertility of sea waters: Cambridge, Mass., Cambridge Univ. Press, 224 p.

Henbest, L. G., 19-56, Foraminifera and correlation of the Ten- sleep sandstone of Pennsylvanian age in Wyoming, in Wyo ming Geol. Assoc. Guidebook llth Ann. Field Conf., 1956: p. 58-63.

Holmes, Arthur, 1960, A revised geologic time scale: Edinburgh Geol. Soc. Trans., v. 17, p. 183-216.

Holmes, R. W., 1957, Ecology, v. 1 of Solar radiation, submarine daylight, and photosynthesis treatise on marine ecology and paleoecology: Geol. Soc. America Mem. 67, p. 109-128.

Honkala, F. S., 1953, Preliminary report on geology of Centen nial Range, Montana-Idaho: U.S. Geol. Survey open-file report, June 22, 1953, 19 p.

Huleatt, W. P., 1950, Automatic sample preparation saves time, money for U.S.G.S.: Eng. Mining Jour., v. 151, p. 62-67.

Humphreys, D. W., 1956, Some problems of size and sorting in sands: Geol. Mag. [Great Britain], v. 93, p. 491-503.

Iddings, J. P., and Weed, W. H., 1894, Livingston atlas sheet [Montana] : U.S. Geol. Survey Geol. Atlas, Folio 1.

Her, R. K., 1955, The colloid chemistry of silica and silicates: Ithaca, N.Y., Cornell Univ. Press, 324 p.

Tiling, L. V., 1954, Bahaman calcareous sands: Am. Assoc. Petroleum Geologists Bull., v. 38, p. 1-95.

Ingram, R. L., 1953, Fissility of mudrocks: Geol. Soc. America Bull., v. 64, p. 869-878.

Inman, D. L., 1949, Sorting of sediments in the light of fluid mechanics: Jour. Sed. Petrology, v. 19, p. 51-70.

Inman, D. L., and Chamberlain, J. K., 1955, Particle-size dis tribution in nearshore sediments: Soc. Econ. Paleontol ogists and Mineralogists Spec. Pub. 3, p. 106-127.

Kazakov, A. V., 1937, The phosphorite facies and the genesis of phosphorites, in Geological investigations of agricultural ores: Sci. Inst. Fertilizers and Insecto-Fungicides Trans., no. 142 (published in Leningrad for the 17th sess. Internat. Geol. Gong.), p. 95-113.

1950, The fluorapatite equilibrium system in the con ditions of formation of sedimentary rocks: Akad. Nauk SSSR, Inst. Geol. Nauk Trudy., Geol. ser., v. 114, no. 40, p. 1-21.

Kennedy, G. C., 1949, Preliminary report on the geology of a portion of the southeast one-fourth of the Lyon quadrangle, Montana-Idaho : U.S. Geol. Survey open-file report, June 14. 1949, 19 p.

Kerr, P. F., Hamilton, P. K., and Phil, R. J., 1950 X-ray dif fraction measurements and chemical analyses in Analytical data on reference clay minerals: Am. Petroleum Inst. Project 49, Clay Mineral Standards, Prelim. Rept. 7, p. 1-58.

Keulegan, G. H., and Krumbein, W. C., 1949, Stable configura tion of bottom slope in a shallow sea and its bearing on geological processes: Am. Geophys. Union Trans., v. 30, p. 855-861.

Klepper, M. R., 1950, A geologic reconnaissance of parts of Beaverhead and Madison Counties, Montana: U.S. Geol. Survey Bull. 969-C, 85 p.

Klepper, M. R., Weeks, R. A., and Ruppel, E. T., 1957, Geology of the southern Elkhorn Mountains, Montana: U.S. Geol. Survey Prof. Paper 292, 82 p.

Krauskopf, K. B., 1955, Sedimentary deposits of rare minerals, in pt. 1 of Bateman, A. M., ed., Economic geology, 50th anniversary volume: Urbana, 111., Econ. Geology Pub. Co., p. 411-463.

Krumbein, W. C., and Garrels, R. M., 1952, Origin and classifi cation of chemical sediments in terms of pH and oxidation- reduction potentials: Jour. Geology, v. 60, p. 1-33.

Krynine, P. D., 1946, The tourmaline group in sediments: Jour. Geology, v. 54. p. 64-87.

1948, The megascopic study and field classification of sedimentary rocks: Jour. Geology, v. 56, p. 130-165.

Kummel, Bernhard, 1954, Triassic stratigraphy of southeastern Idaho and adjacent areas: U.S. Geol. Survey Prof. Paper 254-H, p. 165-194.

Love, J. D., Wertz, J. L., and Hose, R. K., 1955, Geologic map of Wyoming: U.S. Geol. Survey. Scale, 1:500,000.

Lowell, W. R., 1949, Geology of the Small Horn Canyon, Daly's Spur, Cedar Creek, and Dell areas, southwestern Montana: U.S. Geol. Survey open-file report, Dec. 8, 1949.

1952, Phosphatic rocks in the Deer Creek-Wells Canyon area, Idaho: U.S. Geol. Survey Bull. 982-A, p. 1-52.

1953, Geologic map and structure sections of the south west quarter Willis quadrangle, Beaverhead County, Mon tana : U.S. Geol. Survey open-file report, Mar. 30, 1953.

1955, Igneous intrusions and metamorphism in somephosphatic rocks of southwestern Montana: Econ. Geology, v. 50, p. 715-737.

McKee, E. D., Oriel, S. S., Swanson, V. E., MacLachlan, M. E., MacLachlan, J. G., Ketner, K. B., Goldsmith, J. W., Bell, R. Y., and Jameson, D. J.', 1956, Paleotectonic maps of the Jurassic system: U.S. Geol. Survey Misc. Geol. Inv. Map 1-175.

McKee. E. D., Oriel, S. S., Ketner, K. B., MacLachlan, M. E., Goldsmith, J. W., MacLachlan, J. C., and Mudge, M. R., 1959, Paleotectonic maps of the Triassic system : U.S. Geol. Survey Misc. Geol. Inv. Map 1-300.

McKelvey, V. E., 1949, Geological studies of the western phos phate field, in Symposium on western phosphate mining: Mining Eng., v. 1, p. 270-279.

McKelvey, V. E., and Carswell, L. D., 1956, Uranium in Phos- phoria formation, in Page, L. R., Stocking, H. E., and Smith, H. B., Contributions to the geology of uranium and thorium by the United States Geological Survey and Atomic Energy Commission for the United Nations International Con ference on Peaceful Uses of Atomic Energy, Geneva, Switzerland', 1955: U.S. Geol. Survey Prof. Paper 300, p. 483-487.

McKelvey, V. E., Swanson, R. W., and Sheldon, R. P., 1953, the Permian phosphorite deposits of western United States: Internat. Geol. Cong., 19th Algiers, 1952, Comptes rendus, sec. 11, p. 45-64.

McKelvey, V. E., and others, 1956, Summary description of Phosphoria, Park City, and Shedhorn formations in western phosphate field: Am. Assoc. Petroleum Geologist Bull., v. 40, p. 2826-2863.

1959, The Phosphoria, Park Oity Shedhorn, and Lima formations in the western phosphate field: U.S. Geol. Sur vey Prof. Paper 313-A, p. 1-47.

McMannis, W. J., 1955, Geology of the Bridger Range, Montana : Geol. Soc. America Bull., v. 66, 1385-1430.


Mann, J. A., 1950, Geology of part of the Gravelly Range area, Montana: Princeton Univ., Doctoral Dissert. Ser., Pub. 10,962.

Mansfield, G. R., 1927, Geography, geology, and mineral re sources of part of southeastern Idaho: U.S. Geol. Survey Prof. Paper 152, 453 p.

Moore, H. B., 1931, Chemical and physical conditions; rate and nature of sedimentation; and fauna, [pt.] 3 of The muds of the Clyde Sea area: Marine Biol. Assoc. Jour., new ser., v. 17, p. 325-358.

Myers, W. B., 1952, Geology and mineral deposits of the north west quarter of Willis quadrangle and adjacent Browns Lake area, Beaverhead County, Montana: U.S. Geol. Sur vey open-file report, July 28, 1952, 46 p.

Newell, N. D., and Rigby, J. K., 1957, Geological studies on the Great Bahama Bank, in LeBlanc, R. J., and Breeding, J. G., eds., Regional aspects of carbonate deposition a symposium: Soc. Econ. Paleontologists and Mineralogists Spec. Pub. 5, p. 15-72.

Packham, G. H., 1955, Volume-, weight-, and number-frequency analysis of sediments from thin-section data : Jour. Geology, v. 63, p. 50-58.

Pardee, J. T., 1913, Some further discoveries of rock phosphate in Montana: U.S. Geol. Survey Bul. 530-H, p. 285-291.

1950, Late Cenozoic block faulting in western Montana:Geol. Soc. America Bull., v. 61, p. 359-406.

Peale, A. C., 1893, The Paleozoic section in the vicinity of ThreeForks, Montana : U.S. Geol. Survey Bull. 110, 56 p.

1896, Description of the Three Forks sheet [Montana] : U.S. Geol. Survey Geol. Atlas, Folio 24.

Pelto, C. R., 1954, Mapping of multicomponent systems: Jour. Geology,v. 62, p. 501-511.

Poole, F. G., 1957, Paleo-wind directions in late Paleozoic and early Mesozoic time on the Colorado Plateau as determined by cross-strata [abs.] : Geol. Soc. America Bull., v. 68, p. 1870.

Prokopovich, Nichola, 1952, Primary sources of petroleum and their accumulation: Am. Assoc. Petroleum Geologists Bull., v. 36, p. 878-883.

Rankama, Kalervo, 1954, Isotope Geology: London, Pergamon Press. 535 p.

Redfield, A. C., 1958, The biological control of the chemical fac tors in the environment: Am. Scientist, v. 46, p. 205-221.

Reeside, J. B., Jr., 1944, Maps showing thickness and general character of the Cretaceous deposits in the western interior of the United States: U.S. Geol. Survey Oil and Gas Inv. (Prelim.) Map 10.

Revelle, R. R., 1953, Shipboard report, Capricorn expedition: Scripps Inst. Oceanography, SIO Reference 53-15.

Richards, F. A., and Redfield, A. C., 1954, A correlation between the oxygen content of sea water and the organic content of marine sediments : Deep-Sea Research, v. 1, p. 279-281.

Richards, F. A., and Vaccaro, R. F., 1956, The Cariaco Trench, an anaerobic basin in the Caribbean Sea: Deep-Sea Re search, v. 3, p. 214-228.

Richards, R. W., and Mansfield, G. R., 1912, The Bannock over- thrust ; a major fault in southeastern Idaho and north eastern Utah : Jour. Geology, v. 20, p. 683-689.

Richards, R. W., and Pardee, J. T., 1925, The Melrose phosphate field, Montana: U.S. Geol. Survey Bull. 780-A, p. 1-32.

Riley, G. A., Stommel, H., and Bumpus, D. F., 1949, Quantitative ecology of the plankton of the western North Atlantic: Yale Univ., Oceanographic Lab., v. 12, p. 1-169.

Rittenhouse, Gordon, 1943, The transporation and deposition ofheavy minerals: Geol. Soc. America Bull., v. 54, p.1725-1780.

Rooney, L. F., 1956, Organic carbon in Phosphoria formation:Am. Assoc. Petroleum Geologists Bull., v. 40, p. 2267-2271.

Ross, C. P., 1927, Ore deposits in Tertiary lava in the SalmonRiver Mountains, Idaho: Idaho Bur. Mines and GeologyPam. no 25, 21 p.

1934, Correlation and interpretation of Paleozoic strati graphy in south-central Idaho: Geol. Soc. America Bull., v.45, p. 937-1000.

Ross, C. P., Andrews, D. A., and Witkind, I. J., 1955, Geologicmap of Montana : U.S. Geol. Survey. Scale, 1: 500,000.

Ross, C. P., and Forrester, J. D., 1947, Geologic map of the Stateof Idaho: U.S. Geol. Survey. Scale 1: 500,000.

Rubey, W. W., 1933, The size distribution of heavy mineralswithin a water-laid sandstone: Jour. Sed. Petrology, v. 3,p. 3-29.

Ryther, J. H., and Yentsch, C. S., 1958, Primary production ofcontinental shelf waters off New York: Limnology andOceanography, v. 3, p. 327-335.

Sahinen, U. M., 1939, Geology and ore deposits of the Rochesterand adjacent mining districts, Madison County, Montana:Montana Bur. Mines and Geology Mem. 19.

1950, Geology and ore deposits of the Highland Moun tains, southwestern Montana: Montana. Bur. Mines and Geology Mem. 32.

Scholten, Robert, 1957, Paleozoic evolution of the geosynclinal margin north of the Snake River Plain, Idaho-Montana: Geol. Soc. America Bull., v. 68, p. 151-170.

Scholten, Robert, Keenmon, K. A., and Kupsch, W. O., 1955 Geology of the Lime region, southwestern Montana and adjac'ent Idaho: Geol. Soc. America Bull., v. 66, p. 345-404.

Scott, H. W., 1935, Some carboniferous stratigraphy in Montana and northwestern Wyoming: Jour. Geology, v. 43, p. 1011- 1032.

Sheldon, R. P., 1957, Physical stratigraphy of the Phosphoria formation in northwestern Wyoming: U.S. Geol. Survey Bull. 1042-E, p. 105-185.

1959, Geochemistry of uranium in phosphorites and black shales of the Phosphoria formation: U.S. Geol. Survey Bull. 1084-D, p. 83-115.

1963, Physical stratigraphy and mineral resources ofPermian rocks in western Wyoming: U.S. Geol. SurveyProf. Paper 313-B, p. 49-272.

Shepard, F. P., 1956, Marginal sediments of Mississippi delta:Am. Assoc. Petroleum Geologists Bull., v. 40, p. 2537-2623.

Smulikowski, Kazimierz, 1954, The problem of glauconite:Polska Akad. Nauk Kom., Geol. Arch. Mineral, v. 18, p.21-120.

Sonnenberg, F. P., 1956, Tectonic patterns of central Montana,m Billings Geol. Soc. Guidebook 7th Ann. Field Conf.,Aug. 1956: p. 73-81.

Stetson, H. C., 1939, Summary of sedimentary conditions onthe continental shelf off the east coast of the United States,in Trask, P. D., ed., Recent marine sediments, a symposium :Tulsa, Okla., Am. Assoc. Petroleum Geologists, p. 230-244.

Stone, R. W., and Bonine, C. A., 1914, The Elliston phosphatefield, Montana: U.S. Geol. Survey Bull. 580-N, p. 373-383.

Sverdrup, H. U., 1938, On the process of upwelling: Jour.Marine Research, v. 1, p. 155-164.

Sverdrup, H. U., Johnson, M. W., and Fleming, R. H., 1942, Theoceans, their physics, chemistry, and general biology: NewYork, Prentice-Hall, 1,087 p.


Swanson, R. W., 1951, Geology of a part of the Virginia City and Eldridge quadrangles, Montana: U.S. Geol. Survey open-file report, March 8, 1951, 12 p.

Swanson, R. W., Lowell, W. R., Cressman, E. R., and Bostwick, D. A., 1953, Stratigraphic sections of the Phosphoria for mation in Montana, 1947-48: U.S. Geol. Survey Circ. 209, 31 p.

Swineford, Ada, and Franks, P. C., 1959, Opal in the Ogallala formation in Kansas, in Ireland, H. A., ed., Silica in sedi ments, a symposium: Soc. Econ. Paleontologists and Min eralogists Special Pub. 7, p. 111-120.

Taliaferro, N. L., 1933, The relation of volcanism to diato- niaceous and associated siliceous sediments: California Univ. Dept. Geol. Sci., Bull., v. 23, p. 1-56.

Tanner, W. F., 1956, Size and roundness in sediments a discussion: Geol. Soc. America Bull. 67, p. 536.

Thompson, M. E., 1953, Distribution of uranium in rich phos phate b'eds of the Phosphoria formation: U.S. Geol. Survey Bull. 988-D, p. 45-67.

Thompson, M. E., 1954, Further studies in the distribution of uranium in rich phosphate beds of the Phosphoria forma tion : U.S. Geol. Survey Bull. 1009-D, p. 107-123.

Trask, P. D., 1937, Relation of salinity to the calcium carbonate content of marine sediments: U.S. Geol. Survey Prof. Paper 186-N, p. 273-299.

1939, Organic content of recent marine sediments, in Trask, P. D., ed., Recent marine sediments, a symposium: Tulsa, Okla., Am. Assoc. Petroleum Geologists, p. 428-453.

U.S. Dept. Agriculture Yearbook, 1941.

Van Vloten, Roger, 1954, Geology of the border region betweenCoahuila and Zacatecas, Mexico: Leidse Geol. Mededeel.,v. 19, p. 111-165.

Wager, L. R., Weeden, D. S., and Vincent, E. H., 1953, Agranophyre from Coire Uaigneich, Isle of Skye, containingquartz paramorphs after tridymite: Mineralog. Mag., v. 30,p. 263-275.

Weaver, C. E., 195o, Mineralogy and petrology of the rocksnear the Quadrant-Phosphoria boundary in southwestMontana: Jour. Sed. Petrology, v. 25, p. 163-192.

Wentworth, C. K., 1922, A scale of grade and class termsi forclastic sediments: Jour. Geology, v. 30, p. 377-392,

Weyl, W. A., 1953, Melting of solids as influenced by thepolarizability of surface ions, in Gomer, Robert, and Smith,C. S., eds., Structure and properties of solid surfaces:Chicago, Chicago Univ. Press, p. 147-180.

White, D. E., Brannock, W. W., and Murata, K. J., 1956, Silicain hot-spring waters: Geochim. et Cosmochim. Acta, v. 10,p. 27-59.

Wickman, F. E., 1952, Variations in the relative abundance ofthe carbon isotopes in, plants: Geochim. et Cosmochim.Acta, v. 2, p. 243-254.

Williams, J. Stewart, 1953, Pennsylvanian and Permian rocks,in Intermountain Assoc. Petroleum Geologists Guidebook,4th Ann. Field Cont, 1953: p. 38-40.

Wilson, C. W., Jr., 1934, Geology of the thrust fault nearGardiner, Montana: Jour. Geology, v. 42, p. 649-663.

ZoBell, C. E., 1946, Marine microbiology: Waltham, Mass.,Oronica Botanica, 240 p.

INDEX

PageAcid insoluble, analyses of__________ 279,280 Acknowledgments..... _ _ T ___________ 276Alpine Creek- __ ._ 291,296, 299, 324, 335,355, 506 Aluminum, analyses of.____________ 880 Ammonites..___________________ 355 Amsden Formation__. ____________ 355 Anatase. ___________________ 294,344 Angola._-------_-.______________ 374Anticlines-_____________________ 319 Apatite, general discussion. -_-________ 279,

294, 308, 316, 330,342, 344,351 solubility of _____________ 374 trace minerals in________ ____ 319

Aphanitic dolomite in the Park City Forma tion . _...--_ 291

Aspen Valley________. ___.._..__ 392

BBahama Bank. ..-_-___________ 377 Bahaman calcareous sands, phosphorites

compared to____________ 312 Bear Creek____________________ 338 Beaverhead Range _______ 288, 364,379,380 Bibliography__...... 297, 300,304,313, 319, 341,562Big Cottonwood Canyon, Utah________ 286 Big Hole Canyon-Melrose________ 290,297,334 Big Hole Range------..-..__________ 336Bighorn Basin-._________________ 362 Big Sheep Canyon _____ 289,290,294,306,337 Bitterroot Range. ________________ 364 Blacktail Creek_--.._..___________ 347 Blacktail Mountains...____________ 329 Boulder batholith. _______________ 319,320 Brachiopods_-__________________ 291 Bryozoans_____________________ 291 Burrowing organisms______________ 367

CCalifornia current..._____________ 379 Camp Frigid-.-._-______________ 5^6 Canyon Camp_._______________ 335,509 Canyon Creek No. 1_______________ 441 Canyon Creek No. 2_____________ 441 Canyon Creek No. 3.______________ 541 Cap limestone_____ ____________ 333 Carbonaceous matter, analyses of._____ 279,280

clay-particle alinement affected by____ 313 rate of production of ------- _.. ___ 373Retort Phosphate Shale Member contain

ing. .. ______ 305 source of__________________ 373 tourmaline containing..__________ 344

Carbonate rock, defined. _________ __ 282 general discussion.,..__________ 3/5,378 Park City Formation containing.. ___ 280

Carbonate-fluorapatite... __________ 308 Cariaco Trench. _________________ 379 Caribou Range, Idaho._____________ 338 Casto area, Idaho__..........______ 364Casto Volcanics..-______________ 363,379 Cave Creek._________________ 334,473 Cedar Creek___________________ 470 Centennial Mountains...________ 323,338,347 Centennial No. 1. _______________ 464

[Italic page numbers indicate major references]

PageCentennial No. 2, Idaho___________ 468 Centennial No. 3.______________ 467 Central Montana Platform._._..._-.-_.... 362Chalcedony.-.. . ..... . .._... 296,316,372Chemical analyses, general discussion.____ 270Chert, carbonaceous matter in_________ 316

defined.------- .. ___________ 282diagenesis of--_________-_____ 371 general discussion....__________ 3/5,351Park City Formation containing.....__ 296Shedhorn Sandstone containing...-___ 847 source of . ___ 369 total volume of______________ 360

Cherty Shale Member of Phosphoria Forma tion, stratigraphy of._____ 336

Cinnabar Mountain._________ 330,351,5^7 Clay....________-___....___ 296,313,316Climate..__-_____ _______ _ 277 Clyde Sea._..._________________ 375 Color, defined__________________ 282 Commercial phosphorite, production of. - 320 Continental shelf, production of organic car

bon on_______________ 370 Corals.______________________ 354 Cratonicshelfs...________________ 380 Crooked Creek-___...______ .._ 481 Current action, evidence for__.. ._. 310 Currents-- . _ 364,370,373,377,379

D

D function, calculation of____________ 283 Dalys Spur .___-__________ 294,297,357 Dark mudstone. See Mudstone. Demospongia_ _______ _. 371 Depositional basins__________ __ 360 Diatoms __.__-_._.________ 369 Dikes.-.._____.______.___ 320 Dillon-____.__________ 297,300,357 Dinwoody Formation. __________ 336,350,355 Dolomite, defined..________-______ 282

Shedhorn Sandstone containing... _ 847 Drainage._ _ #76

EEast Pacific Ridge. ______ _ 372 Ellis Group _________________ 354 Ervay Tongueof the Park City Formation.. 354 Eugeosynclinal deposits..____ 380 Evaporites.. __ _____ 361

F

Facies, general discussion_ ______ . 355,357See also particular interval.

False cap limestone._________-----_ 333Fault scarps- - 278 Faults-______________________ 278 Faunal zones. ____________ _ 355 Florida straits__________________ 373 Folds . 278Fort Hall, Idaho _.________-__ 333 Fossils _ ____-_____ 315,347,351,354

See also particular formation.

PageFranson Canyon, Utah___ 300 Franson interval___-___ 357 Franson Member of Park City Formation,

general discussion 285 carbonate rock in_____ 289 chert in .-______ __ _ 206 mudstone in__ __ 294 sandstone in_______ 292 stratigraphy of--.-- 300 thickness of - _-_ - 300

Fusulinids _-____ 299,354

GGallatin River ___~_ __ . 288,394 Garnet. 294, 844Garnet Range. __ __ - 350 Garrison.. 350 Geodal vugs.__ __ 336 Geography... 276 Geology, general discussion 277 Geosynclines 380 Glauconite... _ -________ 341,842,351,357,367 Grade scale, defined_____ _ 282 Grain, defined- 282 Grain-size distribution, relation to environ

ments--_______ ... 364 Grandeur Member of Park City Formation,

carbonate rock in. 289,297 chert in _ - __ 297 illustration of. 283mudstone in.___________ 294,297sandstone in.._______ 292,297stratigraphy of. _ - - - 285,296

Gravelly Range.- ________ . 335,347,356Greenstone Gulch-. . 334Gros Ventre Range, Wyo - 335,350,354Gulf of Mexico. __-___ ____- 364

HHardness, defined.-_____ 282 Hawley Creek _____.. 288,290,297,335,336,558 Heath Formation --.-.. .. 355 Heavy minerals, in Shedhorn Sandstone 342 Heavy-mineral separation. 28i Historical geology, summary of events 381 Hogback Mountains....... 293,297,328,335,357, 486

Idaho batholith - 363 Ulite ...____-_________-___ 294,296, 315 Illustrations__ 282 Indian Creek.__.__-__ 339,347,355, 543 Indonesia, glauconite in 367 Intrusives. 319 Investigations, methods of field procedures.... 278

purpose of 276 Iron, analyses of. 280 Ironoxides - 316,342

Jack Canyon. . - 320,335,^02 Jefferson Canyon 531 Jefferson River.. 354

567

568 INDEX

K PageKaolinlte._____________________ 296 Kelly Gulch.._____________ 294,320,334,457

La Jolla, Calif.__.__...______ 364,366,368 La Marche Gulch. _________________ 553 Laboratory procedures_______-_____ 279 Lag deposits._.._______________ 364 Land areas, Permian...____________ 379 Landon Ridge-__________________ 543 Laramide orogeny________________ 278 Lazyman Hill.____________ 299,317,324, 614 Lemhi Range, Idaho.._________ 300,364,380 Leucoxene__________________ 294,343,344 Lima.____________________ 300,349,357 Limestone, defined_______________ 882 Lithologic classes, defined..._________ 883 Little Sheep Creek....__________ 294,337,476 Little Water Canyon______________ 519 Logan_______________________ 556 Loss on ignition, analyses of_________ 279,280 Lower Grandeur interval____________ 356 Lower Member of the Shedhorn Sandstone,

stratigraphy of___________ 347 Lower phosphorite of the Meade Peak Mem

ber._________.______ 383 Lower Tosi interval..______________ 357

MMadison Formation.._____________ 355Madison Range.._______________ 297,347Maiden Rock mine_______________ 320Martha's Vineyard______ _________ 366Meade Peak interval. _____________ 357Meade Peak Phosphatic Shale Member of

Phosphoria Formation, generaldiscussion______... 285,315,319,338

lithologic variations in___________ 323phosphate in.._______________ 308lower phosphorite..____________ 383stratigraphy of...._____________ 230

Melrose Adit No. 1_______________ 443Melrose Adit No. 2_______________ 448Melrose district..._______________ 333Metamorphism, contact____________ 319Mica.______________________ 296Microcrystalline apatite, defined..._____ 308Mississippi delta area_____________ 366,367Mississippi River, silica precipitated from.... 369Monterey Formation______________ 372Mount Fleecer__________________ 319Mudstone, bimodal frequency distribution of. 376

defined.__________________._ 282environment of deposition________ S67,374general discussion...____________. 3/3Park City Formation containing- ____ 294source areas.-- _____ ________ 367,373

NNodule, defined______________ 282,310,332 "North Big Hole Canyon.._._________ 537 North Boulder Creek______________ 649

O

Ocean currents. See Currents. Odell Creek..____________.____ 402 Ogallala Formation_______________ 372 Oil-shale analyses, at Sheep Creek______ 438 Oolite, defined. _______________ 282,309 Oolitic sand__.________________. 377 Organic carbon..............________ 370Otter Formation... _______________ 355

P PagePaleogeographic maps.____________ 378Paleogeography... 378Park City Formation, carbonate rock in___ 378

chert in____________________ 303distribution_________________ 286fossils in____________________ 299general character.... ____.... 285,286lithology of __ - __.__ 289

Pelecypods.____ ____ 291Pellet, defined..______________ 282,309,314Pellets, origin of-_ - 375Permian rocks, age of__ __________ 354

origin of ___________________ 357, 459relation to overlying beds __..___ 354

Permian Sea, transgression and regression _. 380Phosphate, localization of minable deposits__ 338Phosphatic mudstone. See Mudstone.Phosphoria Formation, carbonate rock in__ 378

contact metamorphism in_________ 3/9distribution .. .____________ 303fossils in _________ _.._ 305,315general character.-. 285,303intrusives in.- __ _____ 320lithology of - __- 305minor rock types in ________ 3/7stratigraphy 320trace elements in _.... 3/8See also particular member.

Phosphoria Gulch area, Idaho________ 326,349Phosphorite, defined..... __ ...___ 282

general discussion . ._ 307,377uranium in.. 319

Phosphorus, manner of deposition__.____ 374source of... 374,377

Phosphorus pentoxide, analyses of ._. 279Phytoplankton._ __. .... 373Pioneer Mountains 350Pipette analyses_ 28/Planktonic organisms___.____ ____ 375Porcupine Creek-. 399Precipitation_____ _ __ __ 277Pulpit Rock 349,559

QQuadrant Formation.____ 277,284,298,355 Quadrant Mountain__ 351

RRadiolaria . - 369Reas Peak....__.. . 355Red Creek __..._-_____. 354Red Mudstone. See Mudstone.Red Rock Valley 350Red beds __-___-___ _... 361 Retort interval- - 357 Retort Mountain___ 329 Retort Phosphatic Shale Member of the Phos

phoria Formation, carbonaceous matter in... _____ . 305

facies in______-____ 331 Retort Phosphatic Shale Member, at Hog

back Mountain__________ 317 illustration of __._._ 283,285, 313,315 phosphorite in________________ 308 stratigraphy of. 329

Rex Chert Member of Phosphoria Formation,iron in. . 316

stratigraphy of... 325Rex interval-.-__________ 357Rock source areas, sandstone from 359 Rock terms________ ___ 282 Rockport, Tex_ _____________ 364,366,368 Ruby River... 297

PageRuby Valley. _________________ 356 Rutile.. .......__I______.. 294,343,344

Samples, methods of collecting_________ 278treatment of_________________ 279

Sandstone columns_______________ 351Sandstone, defined...______________ 282

environment of deposition________ 364,367origins of ._ ____ __ 359Park City Formation containing..____ 292Shedhorn Sandstone containing-...___ 339

Sandstone source area, lithologic character.. 359, 367location of_________________ 36/,367

Santa Cruz Basin. ________________ 371Sappington Canyon.______________ 534Sawtooth Mountain___________ 335,347,444Seven Devils__________________ 364,379Seven Devils Volcanics____________ 363Shedhorn Sandstone_______________ 285

general distribution_____________ 338heavy minerals in... ..__ . 342lithology..... ______________ 339stratigraphy of..... ____ .. .. 347

Sheep Creek...__ 306,329,332,334,336, 374,376,426Shell Canyon _________.__ 335,336,355,384Silica, mechanism of precipitation of _ .. 372

rate of deposition of______ _ 369See also Chert.

Silicofiagellates.__ _.__ 369 Sills.___. _________.__ __ 319,320 Sixteen Mile Creek__________.____ 354 Size analyses... -. 2&1 Skeletal carbonate rock in the Park City For

mation_ _____ ... 291 Skeletal dolomite___________.____ 378 Skeletal fragment, defined.. ___ . .. 283,309 Sliderock Mountain._____________ 329,406 Snowcrest Range.______ 297,323,335,347,355,357 South Big Hole Canyon No. 1_________ 528 South Big Hole Canyon No. 2.._.. . SSO South Boulder Creek____________ 335,550 Southwest Africa__ ______ 374 Spectrographic analyses.. _ .. 280

Sheep Creek ____________ 439 Sponges, ability to extract silica from sea

water._________ 369 Sponge spicules-____ 315, 316, 341, 351, 367, 369,371 Spring Creek___.__. ___ 46! Stocks.._______________ 319 Stratigraphic nomenclature, current usage 285

history of.__________________ 284 Stratigraphic sections, general discussion. 383

See also particular locality.Swales.___________ . 315 Sweetgrass Arch..._________ 362

T

Tan Mudstone. See Mudstone. Taylor Creek Ridge, Idaho_ 523 Tectonism-_______________ __ 380 Tendoy Mountains...___ 323, 334, 354, 355, 364, 380 Terminology used._____ 282 Teton Formation..______ 284 Teton Range, Wyo_________ 354 Thickness of bedding, defined. __ 282 Thin sections___________ 280 Three Forks area...____ 294,298, 335,349, 354, 533 Tidal currents. See Currents.

INDEX 569

Page Page PageTime horizons. _________________ 355 Upper Member of the Shedhorn Sandstone, West Fork of Blacktail Creek. .. 335,500Tosi Chert Member of Phosphoria Formation, stratigraphy of. __________ 360 West Fork of Madison River _ ____ 513

general discussion ______ 285,317 Upper Tosi interval. ________ ___ 367 Wigwam Creek 355,56;stratigraphy of ... ____________ SS6 Uranium. _________________ 279,280,3^9 Williston Basin.. _ ___ 361

Tourmaline. . ______________ 294,343,344 Wood River Formation..-.. . 300,379Transportation ____ . ____________ £77 v Woodside Formation. . 300

Turbidity currents. See Currents. Volcanic ash.......... ______ .__ _ 369

w U X-ray analyses.... _ 281

Wadhams Spring... 289, 294, 296, 297, 329, 336, 347, 450 United States Bureau of Mines.. - ... 279 Warm Springs Creek. ___ ___ ........ 365,494 zUpper Grandeur interval __ - ________ S67 Wells formation. ________________ 300 Zircon ____________________ 294,343,344

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